Add "What's This?" to nearly everything in the main window

Summary:
This commit adds "What's This?" help to nearly everything in the
Dolphin main window (panels, views, buttons, ...). It adds the "?"
to the title bar so this help can easily be called.

For links in those help texts to work the WhatsThisClickedEvents are
handled in the main window class. This doesn't work for menus because
events from them aren't forwarded to the main window for some
reason so EventFilters are installed for the Control button menus.

Modifying the "Help" menu of KXmlGui is deprecated so no EventFilter
can be installed in the menubar. Therefore help texts without links
are provided for the menubar.

Test Plan:
Check if the event handling might make any problems.
Check for any big mistakes in the help messages.

Reviewers: #dolphin, elvisangelaccio

Subscribers: broulik, elvisangelaccio, yurchor, kfm-devel

Tags: #dolphin

Differential Revision: https://phabricator.kde.org/D20471

1 files changed, 366 insertions, 9 deletions

diff --git a/src/dolphinmainwindow.cpp b/src/dolphinmainwindow.cpp
index c839e2d5c..ae139d363 100644
--- a/src/dolphinmainwindow.cpp
+++ b/src/dolphinmainwindow.cpp
@@ -72,6 +72,7 @@
 #include <QApplication>
 #include <QClipboard>
 #include <QCloseEvent>
+#include <QDesktopServices>
 #include <QDialog>
 #include <QFileInfo>
 #include <QLineEdit>
@@ -82,6 +83,7 @@
 #include <QStandardPaths>
 #include <QTimer>
 #include <QToolButton>
+#include <QWhatsThisClickedEvent>
 
 namespace {
     // Used for GeneralSettings::version() to determine whether
@@ -90,8 +92,9 @@ namespace {
 }
 
 DolphinMainWindow::DolphinMainWindow() :
-    KXmlGuiWindow(nullptr),
+    KXmlGuiWindow(nullptr, Qt::WindowContextHelpButtonHint),
     m_newFileMenu(nullptr),
+    m_helpMenu(nullptr),
     m_tabWidget(nullptr),
     m_activeViewContainer(nullptr),
     m_actionHandler(nullptr),
@@ -181,6 +184,8 @@ DolphinMainWindow::DolphinMainWindow() :
     auto *middleClickEventFilter = new MiddleClickActionEventFilter(this);
     connect(middleClickEventFilter, &MiddleClickActionEventFilter::actionMiddleClicked, this, &DolphinMainWindow::slotToolBarActionMiddleClicked);
     toolBar()->installEventFilter(middleClickEventFilter);
+
+    setupWhatsThis();
 }
 
 DolphinMainWindow::~DolphinMainWindow()
@@ -318,12 +323,15 @@ void DolphinMainWindow::updateHistory()
     QAction* backAction = actionCollection()->action(KStandardAction::name(KStandardAction::Back));
     if (backAction) {
         backAction->setToolTip(i18nc("@info", "Go back"));
+        backAction->setWhatsThis(i18nc("@info:whatsthis go back", "Return to the previously viewed folder."));
         backAction->setEnabled(index < urlNavigator->historySize() - 1);
     }
 
     QAction* forwardAction = actionCollection()->action(KStandardAction::name(KStandardAction::Forward));
     if (forwardAction) {
         forwardAction->setToolTip(i18nc("@info", "Go forward"));
+        forwardAction->setWhatsThis(xi18nc("@info:whatsthis go forward",
+            "This undoes a <interface>Go|Back</interface> action."));
         forwardAction->setEnabled(index > 0);
     }
 }
@@ -1031,8 +1039,7 @@ void DolphinMainWindow::updateControlMenu()
     addActionToMenu(ac->action(KStandardAction::name(KStandardAction::Preferences)), menu);
 
     // Add "Help" menu
-    auto helpMenu = new KHelpMenu(menu);
-    menu->addMenu(helpMenu->menu());
+    menu->addMenu(m_helpMenu->menu());
 
     menu->addSeparator();
     addActionToMenu(ac->action(KStandardAction::name(KStandardAction::ShowMenubar)), menu);
@@ -1149,40 +1156,82 @@ void DolphinMainWindow::setupActions()
 
     QAction* newWindow = KStandardAction::openNew(this, &DolphinMainWindow::openNewMainWindow, actionCollection());
     newWindow->setText(i18nc("@action:inmenu File", "New &Window"));
+    newWindow->setWhatsThis(xi18nc("@info:whatsthis", "This opens a new "
+        "window just like this one with the current location and view."
+        "<nl/>You can drag and drop items between windows."));
     newWindow->setIcon(QIcon::fromTheme(QStringLiteral("window-new")));
 
     QAction* newTab = actionCollection()->addAction(QStringLiteral("new_tab"));
     newTab->setIcon(QIcon::fromTheme(QStringLiteral("tab-new")));
     newTab->setText(i18nc("@action:inmenu File", "New Tab"));
+    newTab->setWhatsThis(xi18nc("@info:whatsthis", "This opens a new "
+        "<emphasis>Tab</emphasis> with the current location and view.<nl/>"
+        "A tab is an additional view within this window. "
+        "You can drag and drop items between tabs."));
     actionCollection()->setDefaultShortcuts(newTab, {Qt::CTRL + Qt::Key_T, Qt::CTRL + Qt::SHIFT + Qt::Key_N});
     connect(newTab, &QAction::triggered, this, &DolphinMainWindow::openNewActivatedTab);
 
     QAction* closeTab = KStandardAction::close(m_tabWidget, QOverload<>::of(&DolphinTabWidget::closeTab), actionCollection());
     closeTab->setText(i18nc("@action:inmenu File", "Close Tab"));
+    closeTab->setWhatsThis(i18nc("@info:whatsthis", "This closes the "
+        "currently viewed tab. If no more tabs are left this window "
+        "will close instead."));
 
-    KStandardAction::quit(this, &DolphinMainWindow::quit, actionCollection());
+    QAction* quitAction = KStandardAction::quit(this, &DolphinMainWindow::quit, actionCollection());
+    quitAction->setWhatsThis(i18nc("@info:whatsthis quit", "This closes this window."));
 
     // setup 'Edit' menu
     KStandardAction::undo(this,
                           &DolphinMainWindow::undo,
                           actionCollection());
 
-
-    KStandardAction::cut(this, &DolphinMainWindow::cut, actionCollection());
-    KStandardAction::copy(this, &DolphinMainWindow::copy, actionCollection());
+    // i18n: This will be the last paragraph for the whatsthis for all three:
+    // Cut, Copy and Paste
+    const QString cutCopyPastePara = xi18nc("@info:whatsthis", "<para><emphasis>Cut, "
+        "Copy</emphasis> and <emphasis>Paste</emphasis> work between many "
+        "applications and are among the most used commands. That's why their "
+        "<emphasis>keyboard shortcuts</emphasis> are prominently placed right "
+        "next to each other on the keyboard: <shortcut>Ctrl+X</shortcut>, "
+        "<shortcut>Ctrl+C</shortcut> and <shortcut>Ctrl+V</shortcut>.</para>");
+    QAction* cutAction = KStandardAction::cut(this, &DolphinMainWindow::cut, actionCollection());
+    cutAction->setWhatsThis(xi18nc("@info:whatsthis cut", "This copies the items "
+        "in your current selection to the <emphasis>clipboard</emphasis>.<nl/>"
+        "Use the <emphasis>Paste</emphasis> action afterwards to copy them from "
+        "the clipboard to a new location. The items will be removed from their "
+        "initial location.") + cutCopyPastePara);
+    QAction* copyAction = KStandardAction::copy(this, &DolphinMainWindow::copy, actionCollection());
+    copyAction->setWhatsThis(xi18nc("@info:whatsthis copy", "This copies the "
+        "items in your current selection to the <emphasis>clipboard</emphasis>."
+        "<nl/>Use the <emphasis>Paste</emphasis> action afterwards to copy them "
+        "from the clipboard to a new location.") +  cutCopyPastePara);
     QAction* paste = KStandardAction::paste(this, &DolphinMainWindow::paste, actionCollection());
     // The text of the paste-action is modified dynamically by Dolphin
     // (e. g. to "Paste One Folder"). To prevent that the size of the toolbar changes
     // due to the long text, the text "Paste" is used:
     paste->setIconText(i18nc("@action:inmenu Edit", "Paste"));
+    paste->setWhatsThis(xi18nc("@info:whatsthis paste", "This copies the items from "
+        "your <emphasis>clipboard</emphasis> to the currently viewed folder.<nl/>"
+        "If the items were added to the clipboard by the <emphasis>Cut</emphasis> "
+        "action they are removed from their old location.") +  cutCopyPastePara);
 
     QAction *searchAction = KStandardAction::find(this, &DolphinMainWindow::find, actionCollection());
     searchAction->setText(i18n("Search..."));
+    searchAction->setToolTip(i18nc("@info:tooltip", "Search for files and folders"));
+    searchAction->setWhatsThis(xi18nc("@info:whatsthis find", "<para>This helps you "
+        "find files and folders by opening a <emphasis>find bar</emphasis>. "
+        "There you can enter search terms and specify settings to find the "
+        "objects you are looking for.</para><para>Use this help again on "
+        "the find bar so we can have a look at it while the settings are "
+        "explained.</para>"));
 
-    KStandardAction::selectAll(this, &DolphinMainWindow::selectAll, actionCollection());
+    QAction* selectAllAction = KStandardAction::selectAll(this, &DolphinMainWindow::selectAll, actionCollection());
+    selectAllAction->setWhatsThis(xi18nc("@info:whatsthis", "This selects all "
+        "files and folders in the current location."));
 
     QAction* invertSelection = actionCollection()->addAction(QStringLiteral("invert_selection"));
     invertSelection->setText(i18nc("@action:inmenu Edit", "Invert Selection"));
+    invertSelection->setWhatsThis(xi18nc("@info:whatsthis invert", "This selects all "
+        "objects that you have currently <emphasis>not</emphasis> selected instead."));
     invertSelection->setIcon(QIcon::fromTheme(QStringLiteral("edit-select-invert")));
     actionCollection()->setDefaultShortcut(invertSelection, Qt::CTRL + Qt::SHIFT + Qt::Key_A);
     connect(invertSelection, &QAction::triggered, this, &DolphinMainWindow::invertSelection);
@@ -1191,6 +1240,10 @@ void DolphinMainWindow::setupActions()
     // (note that most of it is set up in DolphinViewActionHandler)
 
     QAction* split = actionCollection()->addAction(QStringLiteral("split_view"));
+    split->setWhatsThis(xi18nc("@info:whatsthis find", "<para>This splits "
+        "the folder view below into two autonomous views.</para><para>This "
+        "way you can see two locations at once and move items between them "
+        "quickly.</para>Click this again afterwards to recombine the views."));
     actionCollection()->setDefaultShortcut(split, Qt::Key_F3);
     connect(split, &QAction::triggered, this, &DolphinMainWindow::toggleSplitView);
 
@@ -1208,16 +1261,28 @@ void DolphinMainWindow::setupActions()
     QAction* stop = actionCollection()->addAction(QStringLiteral("stop"));
     stop->setText(i18nc("@action:inmenu View", "Stop"));
     stop->setToolTip(i18nc("@info", "Stop loading"));
+    stop->setWhatsThis(i18nc("@info", "This stops the loading of the contents of the current folder."));
     stop->setIcon(QIcon::fromTheme(QStringLiteral("process-stop")));
     connect(stop, &QAction::triggered, this, &DolphinMainWindow::stopLoading);
 
     KToggleAction* editableLocation = actionCollection()->add<KToggleAction>(QStringLiteral("editable_location"));
     editableLocation->setText(i18nc("@action:inmenu Navigation Bar", "Editable Location"));
+    editableLocation->setWhatsThis(xi18nc("@info:whatsthis",
+        "This toggles the <emphasis>Location Bar</emphasis> to be "
+        "editable so you can directly enter a location you want to go to.<nl/>"
+        "You can also switch to editing by clicking to the right of the "
+        "location and switch back by confirming the edited location."));
     actionCollection()->setDefaultShortcut(editableLocation, Qt::Key_F6);
     connect(editableLocation, &KToggleAction::triggered, this, &DolphinMainWindow::toggleEditLocation);
 
     QAction* replaceLocation = actionCollection()->addAction(QStringLiteral("replace_location"));
     replaceLocation->setText(i18nc("@action:inmenu Navigation Bar", "Replace Location"));
+    // i18n: "enter" is used both in the meaning of "writing" and "going to" a new location here.
+    // Both meanings are useful but not necessary to understand the use of "Replace Location".
+    // So you might want to be more verbose in your language to convey the meaning but it's up to you.
+    replaceLocation->setWhatsThis(xi18nc("@info:whatsthis",
+        "This switches to editing the location and selects it "
+        "so you can quickly enter a different location."));
     actionCollection()->setDefaultShortcut(replaceLocation, Qt::CTRL + Qt::Key_L);
     connect(replaceLocation, &QAction::triggered, this, &DolphinMainWindow::replaceLocation);
 
@@ -1238,21 +1303,37 @@ void DolphinMainWindow::setupActions()
 
     QAction* undoCloseTab = actionCollection()->addAction(QStringLiteral("undo_close_tab"));
     undoCloseTab->setText(i18nc("@action:inmenu File", "Undo close tab"));
+    undoCloseTab->setWhatsThis(i18nc("@info:whatsthis undo close tab",
+        "This returns you to the previously closed tab."));
     actionCollection()->setDefaultShortcut(undoCloseTab, Qt::CTRL + Qt::SHIFT + Qt::Key_T);
     undoCloseTab->setIcon(QIcon::fromTheme(QStringLiteral("edit-undo")));
     undoCloseTab->setEnabled(false);
     connect(undoCloseTab, &QAction::triggered, recentTabsMenu, &DolphinRecentTabsMenu::undoCloseTab);
 
     auto undoAction = actionCollection()->action(KStandardAction::name(KStandardAction::Undo));
+    undoAction->setWhatsThis(xi18nc("@info:whatsthis", "This undoes "
+        "the last change you made to files or folders.<nl/>"
+        "Such changes include <interface>creating, renaming</interface> "
+        "and <interface>moving</interface> them to a different location "
+        "or to the <filename>Trash</filename>. <nl/>Changes that can't "
+        "be undone will ask for your confirmation."));
     undoAction->setEnabled(false); // undo should be disabled by default
 
     KStandardAction::forward(this, &DolphinMainWindow::goForward, actionCollection());
     KStandardAction::up(this, &DolphinMainWindow::goUp, actionCollection());
-    KStandardAction::home(this, &DolphinMainWindow::goHome, actionCollection());
+    QAction* homeAction = KStandardAction::home(this, &DolphinMainWindow::goHome, actionCollection());
+    homeAction->setWhatsThis(xi18nc("@info:whatsthis", "Go to your "
+        "<filename>Home</filename> folder.<nl/>Every user account "
+        "has their own <filename>Home</filename> that contains their data "
+        "including folders that contain personal application data."));
 
     // setup 'Tools' menu
     QAction* showFilterBar = actionCollection()->addAction(QStringLiteral("show_filter_bar"));
     showFilterBar->setText(i18nc("@action:inmenu Tools", "Show Filter Bar"));
+    showFilterBar->setWhatsThis(xi18nc("@info:whatsthis", "This opens the "
+        "<emphasis>Filter Bar</emphasis> at the bottom of the window.<nl/> "
+        "There you can enter a text to filter the files and folders currently displayed. "
+        "Only those that contain the text in their name will be kept in view."));
     showFilterBar->setIcon(QIcon::fromTheme(QStringLiteral("view-filter")));
     actionCollection()->setDefaultShortcuts(showFilterBar, {Qt::CTRL + Qt::Key_I, Qt::Key_Slash});
     connect(showFilterBar, &QAction::triggered, this, &DolphinMainWindow::showFilterBar);
@@ -1267,6 +1348,9 @@ void DolphinMainWindow::setupActions()
     if (KAuthorized::authorize(QStringLiteral("shell_access"))) {
         QAction* openTerminal = actionCollection()->addAction(QStringLiteral("open_terminal"));
         openTerminal->setText(i18nc("@action:inmenu Tools", "Open Terminal"));
+        openTerminal->setWhatsThis(xi18nc("@info:whatsthis",
+            "<para>This opens a <emphasis>terminal</emphasis> application for the viewed location.</para>"
+            "<para>To learn more about terminals use the help in the terminal application.</para>"));
         openTerminal->setIcon(QIcon::fromTheme(QStringLiteral("utilities-terminal")));
         actionCollection()->setDefaultShortcut(openTerminal, Qt::SHIFT + Qt::Key_F4);
         connect(openTerminal, &QAction::triggered, this, &DolphinMainWindow::openTerminal);
@@ -1283,10 +1367,21 @@ void DolphinMainWindow::setupActions()
 
     // setup 'Settings' menu
     KToggleAction* showMenuBar = KStandardAction::showMenubar(nullptr, nullptr, actionCollection());
+    showMenuBar->setWhatsThis(xi18nc("@info:whatsthis",
+            "This switches between having a <emphasis>Menubar</emphasis> "
+            "and having a <interface>Control</interface> button. Both "
+            "contain mostly the same commands and configuration options."));
     connect(showMenuBar, &KToggleAction::triggered,                   // Fixes #286822
             this, &DolphinMainWindow::toggleShowMenuBar, Qt::QueuedConnection);
     KStandardAction::preferences(this, &DolphinMainWindow::editSettings, actionCollection());
 
+    // setup 'Help' menu for the m_controlButton. The other one is set up in the base class.
+    m_helpMenu = new KHelpMenu(nullptr);
+    m_helpMenu->menu()->installEventFilter(this);
+    // remove duplicate shortcuts
+    m_helpMenu->action(KHelpMenu::menuHelpContents)->setShortcut(QKeySequence());
+    m_helpMenu->action(KHelpMenu::menuWhatsThis)->setShortcut(QKeySequence());
+
     // not in menu actions
     QList<QKeySequence> nextTabKeys = KStandardShortcut::tabNext();
     nextTabKeys.append(QKeySequence(Qt::CTRL + Qt::Key_Tab));
@@ -1340,6 +1435,11 @@ void DolphinMainWindow::setupDockWidgets()
     lockLayoutAction->setActiveIcon(QIcon::fromTheme(QStringLiteral("object-unlocked")));
     lockLayoutAction->setInactiveText(i18nc("@action:inmenu Panels", "Lock Panels"));
     lockLayoutAction->setInactiveIcon(QIcon::fromTheme(QStringLiteral("object-locked")));
+    lockLayoutAction->setWhatsThis(xi18nc("@info:whatsthis", "This "
+        "switches between having panels <emphasis>locked</emphasis> or "
+        "<emphasis>unlocked</emphasis>.<nl/>Unlocked panels can be "
+        "dragged to the other side of the window and have a close "
+        "button.<nl/>Locked panels are embedded more cleanly."));
     lockLayoutAction->setActive(lock);
     connect(lockLayoutAction, &KDualAction::triggered, this, &DolphinMainWindow::togglePanelLockState);
 
@@ -1367,6 +1467,24 @@ void DolphinMainWindow::setupDockWidgets()
             infoPanel, &InformationPanel::requestDelayedItemInfo);
 #endif
 
+    // i18n: This is the last paragraph for the "What's This"-texts of all four panels.
+    const QString panelWhatsThis = xi18nc("@info:whatsthis", "<para>To show or "
+        "hide panels like this go to <interface>Control|Panels</interface> "
+        "or <interface>View|Panels</interface>.</para>");
+    actionCollection()->action(QStringLiteral("show_information_panel"))
+        ->setWhatsThis(xi18nc("@info:whatsthis", "<para> This toggles the "
+        "<emphasis>information</emphasis> panel at the right side of the "
+        "window.</para><para>The panel provides in-depth information "
+        "about the items your mouse is hovering over or about the selected "
+        "items. Otherwise it informs you about the currently viewed folder.<nl/>"
+        "For single items a preview of their contents is provided.</para>"));
+    infoDock->setWhatsThis(xi18nc("@info:whatsthis", "<para>This panel "
+        "provides in-depth information about the items your mouse is "
+        "hovering over or about the selected items. Otherwise it informs "
+        "you about the currently viewed folder.<nl/>For single items a "
+        "preview of their contents is provided.</para><para>You can configure "
+        "which and how details are given here by right-clicking.</para>") + panelWhatsThis);
+
     // Setup "Folders"
     DolphinDockWidget* foldersDock = new DolphinDockWidget(i18nc("@title:window", "Folders"));
     foldersDock->setLocked(lock);
@@ -1389,6 +1507,17 @@ void DolphinMainWindow::setupDockWidgets()
     connect(foldersPanel, &FoldersPanel::errorMessage,
             this, &DolphinMainWindow::showErrorMessage);
 
+    actionCollection()->action(QStringLiteral("show_folders_panel"))
+        ->setWhatsThis(xi18nc("@info:whatsthis", "This toggles the "
+        "<emphasis>folders</emphasis> panel at the left side of the window."
+        "<nl/><nl/>It shows the folders of the <emphasis>file system"
+        "</emphasis> in a <emphasis>tree view</emphasis>."));
+    foldersDock->setWhatsThis(xi18nc("@info:whatsthis", "<para>This panel "
+        "shows the folders of the <emphasis>file system</emphasis> in a "
+        "<emphasis>tree view</emphasis>.</para><para>Click a folder to go "
+        "there. Click the arrow to the left of a folder to see its subfolders. "
+        "This allows quick switching between any folders.</para>") + panelWhatsThis);
+
     // Setup "Terminal"
 #ifdef HAVE_TERMINAL
     if (KAuthorized::authorize(QStringLiteral("shell_access"))) {
@@ -1416,6 +1545,22 @@ void DolphinMainWindow::setupDockWidgets()
         if (GeneralSettings::version() < 200) {
             terminalDock->hide();
         }
+
+        actionCollection()->action(QStringLiteral("show_terminal_panel"))
+            ->setWhatsThis(xi18nc("@info:whatsthis", "<para>This toggles the "
+            "<emphasis>terminal</emphasis> panel at the bottom of the window."
+            "<nl/>The location in the terminal will always match the folder "
+            "view so you can navigate using either.</para><para>The terminal "
+            "panel is not needed for basic computer usage but can be useful "
+            "for advanced tasks. To learn more about terminals use the help "
+            "in a standalone terminal application like Konsole.</para>"));
+        terminalDock->setWhatsThis(xi18nc("@info:whatsthis", "<para>This is "
+            "the <emphasis>terminal</emphasis> panel. It behaves like a "
+            "normal terminal but will match the location of the folder view "
+            "so you can navigate using either.</para><para>The terminal panel "
+            "is not needed for basic computer usage but can be useful for "
+            "advanced tasks. To learn more about terminals use the help in a "
+            "standalone terminal application like Konsole.</para>") + panelWhatsThis);
     }
 #endif
 
@@ -1459,6 +1604,9 @@ void DolphinMainWindow::setupDockWidgets()
     auto actionShowAllPlaces = new QAction(QIcon::fromTheme(QStringLiteral("hint")), i18nc("@item:inmenu", "Show Hidden Places"), this);
     actionShowAllPlaces->setCheckable(true);
     actionShowAllPlaces->setDisabled(true);
+    actionShowAllPlaces->setWhatsThis(i18nc("@info:whatsthis", "This displays "
+        "all places in the places panel that have been hidden. They will "
+        "appear semi-transparent unless you uncheck their hide property."));
 
     connect(actionShowAllPlaces, &QAction::triggered, this, [actionShowAllPlaces, this](bool checked){
         actionShowAllPlaces->setIcon(QIcon::fromTheme(checked ? QStringLiteral("visibility") : QStringLiteral("hint")));
@@ -1470,6 +1618,25 @@ void DolphinMainWindow::setupDockWidgets()
         actionShowAllPlaces->setIcon(QIcon::fromTheme(checked ? QStringLiteral("visibility") : QStringLiteral("hint")));
    });
 
+    actionCollection()->action(QStringLiteral("show_places_panel"))
+        ->setWhatsThis(xi18nc("@info:whatsthis", "<para>This toggles the "
+        "<emphasis>places</emphasis> panel at the left side of the window."
+        "</para><para>It allows you to go to locations you have "
+        "bookmarked and to access disk or media attached to the computer "
+        "or to the network. It also contains sections to find recently "
+        "saved files or files of a certain type.</para>"));
+    placesDock->setWhatsThis(xi18nc("@info:whatsthis", "<para>This is the "
+        "<emphasis>Places</emphasis> panel. It allows you to go to locations "
+        "you have bookmarked and to access disk or media attached to the "
+        "computer or to the network. It also contains sections to find "
+        "recently saved files or files of a certain type.</para><para>"
+        "Click on an entry to go there. Click with the right mouse button "
+        "instead to open any entry in a new tab or new window.</para>"
+        "<para>New entries can be added by dragging folders onto this panel. "
+        "Right-click any section or entry to hide it. Right-click an empty "
+        "space on this panel and select <interface>Show Hidden Places"
+        "</interface> to display it again.</para>") + panelWhatsThis);
+
     // Add actions into the "Panels" menu
     KActionMenu* panelsMenu = new KActionMenu(i18nc("@action:inmenu View", "Panels"), this);
     actionCollection()->addAction(QStringLiteral("panels"), panelsMenu);
@@ -1536,6 +1703,16 @@ void DolphinMainWindow::updateGoActions()
 {
     QAction* goUpAction = actionCollection()->action(KStandardAction::name(KStandardAction::Up));
     const QUrl currentUrl = m_activeViewContainer->url();
+    // I think this is one of the best places to firstly be confronted
+    // with a file system and its hierarchy. Talking about the root
+    // directory might seem too much here but it is the question that
+    // naturally arises in this context.
+    goUpAction->setWhatsThis(xi18nc("@info:whatsthis", "<para>Go to "
+        "the folder that contains the currenty viewed one.</para>"
+        "<para>All files and folders are organized in a hierarchical "
+        "<emphasis>file system</emphasis>. At the top of this hierarchy is "
+        "a directory that contains all data connected to this computer"
+        "—the <emphasis>root directory</emphasis>.</para>"));
     goUpAction->setEnabled(KIO::upUrl(currentUrl) != currentUrl);
 }
 
@@ -1549,11 +1726,13 @@ void DolphinMainWindow::createControlButton()
     m_controlButton = new QToolButton(this);
     m_controlButton->setIcon(QIcon::fromTheme(QStringLiteral("application-menu")));
     m_controlButton->setText(i18nc("@action", "Control"));
+    m_controlButton->setAttribute(Qt::WidgetAttribute::WA_CustomWhatsThis);
     m_controlButton->setPopupMode(QToolButton::InstantPopup);
     m_controlButton->setToolButtonStyle(toolBar()->toolButtonStyle());
 
     QMenu* controlMenu = new QMenu(m_controlButton);
     connect(controlMenu, &QMenu::aboutToShow, this, &DolphinMainWindow::updateControlMenu);
+    controlMenu->installEventFilter(this);
 
     m_controlButton->setMenu(controlMenu);
 
@@ -1708,6 +1887,184 @@ void DolphinMainWindow::createPanelAction(const QIcon& icon,
     connect(dockAction, &QAction::toggled, panelAction, &QAction::setChecked);
 }
 
+void DolphinMainWindow::setupWhatsThis()
+{
+    // main widgets
+    menuBar()->setWhatsThis(xi18nc("@info:whatsthis", "<para>This is the "
+        "<emphasis>Menubar</emphasis>. It provides access to commands and "
+        "configuration options. Left-click on any of the menus on this "
+        "bar to see its contents.</para><para>The Menubar can be hidden "
+        "by unchecking <interface>Settings|Show Menubar</interface>. Then "
+        "most of its contents become available through a <interface>Control"
+        "</interface> button on the <emphasis>Toolbar</emphasis>.</para>"));
+    toolBar()->setWhatsThis(xi18nc("@info:whatsthis", "<para>This is the "
+        "<emphasis>Toolbar</emphasis>. It allows quick access to "
+        "frequently used actions.</para><para>It is highly customizable. "
+        "All items you see in the <interface>Control</interface> menu or "
+        "in the <interface>Menubar</interface> can be placed on the "
+        "Toolbar. Just right-click on it and select <interface>Configure "
+        "Toolbars…</interface> or find this action in the <interface>"
+        "Control</interface> or <interface>Settings</interface> menu."
+        "</para><para>The location of the bar and the style of its "
+        "buttons can also be changed in the right-click menu. Right-click "
+        "a button if you want to show or hide its text.</para>"));
+    m_tabWidget->setWhatsThis(xi18nc("@info:whatsthis main view",
+        "<para>Here you can see the <emphasis>folders</emphasis> and "
+        "<emphasis>files</emphasis> that are at the location described in "
+        "the <interface>Location Bar</interface> above. This area is the "
+        "central part of this application where you navigate to the files "
+        "you want to use.</para><para>For an elaborate and general "
+        "introduction to this application <link "
+        "url='https://userbase.kde.org/Dolphin/File_Management#Introduction_to_Dolphin'>"
+        "click here</link>. This will open an introductory article from "
+        "the <emphasis>KDE UserBase Wiki</emphasis>.</para><para>For brief "
+        "explanations of all the features of this <emphasis>view</emphasis> "
+        "<link url='help:/dolphin/dolphin-view.html'>click here</link> "
+        "instead. This will open a page from the <emphasis>Handbook"
+        "</emphasis> that covers the basics.</para>"));
+
+    // Settings menu
+    actionCollection()->action(KStandardAction::name(KStandardAction::KeyBindings))
+        ->setWhatsThis(xi18nc("@info:whatsthis","<para>This opens a window "
+        "that lists the <emphasis>keyboard shortcuts</emphasis>.<nl/>"
+        "There you can set up key combinations to trigger an action when "
+        "they are pressed simultaneously. All commands in this application can "
+        "be triggered this way.</para>"));
+    actionCollection()->action(KStandardAction::name(KStandardAction::ConfigureToolbars))
+        ->setWhatsThis(xi18nc("@info:whatsthis","<para>This opens a window in which "
+        "you can change which buttons appear on the <emphasis>Toolbar</emphasis>.</para>"
+        "<para>All items you see in the <interface>Control</interface> menu "
+        "or in the <interface>Menubar</interface> can also be placed on the Toolbar.</para>"));
+    actionCollection()->action(KStandardAction::name(KStandardAction::Preferences))
+        ->setWhatsThis(xi18nc("@info:whatsthis","This opens a window where you can "
+        "change a multitude of settings for this application. For an explanation "
+        "of the various settings go to the chapter <emphasis>Configuring Dolphin"
+        "</emphasis> in <interface>Help|Dolphin Handbook</interface>."));
+
+    // Help menu
+    // The whatsthis has to be set for the m_helpMenu and for the
+    // StandardAction separately because both are used in different locations.
+    // m_helpMenu is only used for createControlButton() button.
+
+    // Links do not work within the Menubar so texts without links are provided there.
+
+    // i18n: If the external link isn't available in your language you should
+    // probably state the external link language at least in brackets to not
+    // frustrate the user. If there are multiple languages that the user might
+    // know with a reasonable chance you might want to have 2 external links.
+    // The same is in my opinion true for every external link you translate.
+    const QString whatsThisHelpContents = xi18nc("@info:whatsthis handbook",
+        "<para>This opens the Handbook for this application. It provides "
+        "explanations for every part of <emphasis>Dolphin</emphasis>.</para>");
+    actionCollection()->action(KStandardAction::name(KStandardAction::HelpContents))
+        ->setWhatsThis(whatsThisHelpContents
+        + xi18nc("@info:whatsthis second half of handbook hb text without link",
+        "<para>If you want more elaborate introductions to the "
+        "different features of <emphasis>Dolphin</emphasis> "
+        "go to the KDE UserBase Wiki.</para>"));
+    m_helpMenu->action(KHelpMenu::menuHelpContents)->setWhatsThis(whatsThisHelpContents
+        + xi18nc("@info:whatsthis second half of handbook text with link",
+        "<para>If you want more elaborate introductions to the "
+        "different features of <emphasis>Dolphin</emphasis> "
+        "<link url='https://userbase.kde.org/Dolphin/File_Management'>click here</link>. "
+        "It will open the dedicated page in the KDE UserBase Wiki.</para>"));
+
+    const QString whatsThisWhatsThis = xi18nc("@info:whatsthis whatsthis button",
+        "<para>This is the button that invokes the help feature you are "
+        "using right now! Click it, then click any component of this "
+        "application to ask \"What's this?\" about it. The mouse cursor "
+        "will change appearance if no help is available for a spot.</para>");
+    actionCollection()->action(KStandardAction::name(KStandardAction::WhatsThis))
+       ->setWhatsThis(whatsThisWhatsThis
+        + xi18nc("@info:whatsthis second half of whatsthis button text without link",
+        "<para>There are two other ways to get help for this application: The "
+        "<interface>Dolphin Handbook</interface> in the <interface>Help"
+        "</interface> menu and the <emphasis>KDE UserBase Wiki</emphasis> "
+        "article about <emphasis>File Management</emphasis> online."
+        "</para><para>The \"What's this?\" help is "
+        "missing in most other windows so don't get too used to this.</para>"));
+    m_helpMenu->action(KHelpMenu::menuWhatsThis)->setWhatsThis(whatsThisWhatsThis
+        + xi18nc("@info:whatsthis second half of whatsthis button text with link",
+        "<para>There are two other ways to get help: "
+        "The <link url='help:/dolphin/index.html'>Dolphin Handbook</link> and "
+        "the <link url='https://userbase.kde.org/Dolphin/File_Management'>KDE "
+        "UserBase Wiki</link>.</para><para>The \"What's this?\" help is "
+        "missing in most other windows so don't get too used to this.</para>"));
+
+    const QString whatsThisReportBug = xi18nc("@info:whatsthis","<para>This opens a "
+        "window that will guide you through reporting errors or flaws "
+        "in this application or in other KDE software.</para>");
+    actionCollection()->action(KStandardAction::name(KStandardAction::ReportBug))
+       ->setWhatsThis(whatsThisReportBug);
+    m_helpMenu->action(KHelpMenu::menuReportBug)->setWhatsThis(whatsThisReportBug
+        + xi18nc("@info:whatsthis second half of reportbug text with link",
+        "<para>High-quality bug reports are much appreciated. To learn "
+        "how to make your bug report as effective as possible "
+        "<link url='https://community.kde.org/Get_Involved/Bug_Reporting'>"
+        "click here</link>.</para>"));
+
+    const QString whatsThisDonate = xi18nc("@info:whatsthis","<para>This opens a "
+        "<emphasis>web page</emphasis> where you can donate to "
+        "support the continued work on this application and many "
+        "other projects by the <emphasis>KDE</emphasis> community.</para>"
+        "<para>Donating is the easiest and fastest way to efficiently "
+        "support KDE and its projects. KDE projects are available for "
+        "free therefore your donation is needed to cover things that "
+        "require money like servers, contributor meetings, etc.</para>"
+        "<para><emphasis>KDE e.V.</emphasis> is the non-profit "
+        "organization behind the KDE community.</para>");
+    actionCollection()->action(KStandardAction::name(KStandardAction::Donate))
+       ->setWhatsThis(whatsThisDonate);
+    m_helpMenu->action(KHelpMenu::menuDonate)->setWhatsThis(whatsThisDonate);
+
+    const QString whatsThisSwitchLanguage = xi18nc("@info:whatsthis",
+        "With this you can change the language this application uses."
+        "<nl/>You can even set secondary languages which will be used "
+        "if texts are not available in your preferred language.");
+    actionCollection()->action(KStandardAction::name(KStandardAction::SwitchApplicationLanguage))
+       ->setWhatsThis(whatsThisSwitchLanguage);
+    m_helpMenu->action(KHelpMenu::menuSwitchLanguage)->setWhatsThis(whatsThisSwitchLanguage);
+
+    const QString whatsThisAboutApp = xi18nc("@info:whatsthis","This opens a "
+        "window that informs you about the version, license, "
+        "used libraries and maintainers of this application.");
+    actionCollection()->action(KStandardAction::name(KStandardAction::AboutApp))
+       ->setWhatsThis(whatsThisAboutApp);
+    m_helpMenu->action(KHelpMenu::menuAboutApp)->setWhatsThis(whatsThisAboutApp);
+
+    const QString whatsThisAboutKDE = xi18nc("@info:whatsthis","This opens a "
+        "window with information about <emphasis>KDE</emphasis>. "
+        "The KDE community are the people behind this free software."
+        "<nl/>If you like using this application but don't know "
+        "about KDE or want to see a cute dragon have a look!");
+    actionCollection()->action(KStandardAction::name(KStandardAction::AboutKDE))
+       ->setWhatsThis(whatsThisAboutKDE);
+    m_helpMenu->action(KHelpMenu::menuAboutKDE)->setWhatsThis(whatsThisAboutKDE);
+}
+
+bool DolphinMainWindow::event(QEvent *event)
+{
+    if (event->type() == QEvent::WhatsThisClicked) {
+        event->accept();
+        QWhatsThisClickedEvent* whatsThisEvent = dynamic_cast<QWhatsThisClickedEvent*>(event);
+        QDesktopServices::openUrl(QUrl(whatsThisEvent->href()));
+        return true;
+    }
+    return KXmlGuiWindow::event(event);
+}
+
+bool DolphinMainWindow::eventFilter(QObject* obj, QEvent* event)
+{
+    Q_UNUSED(obj)
+    if (event->type() == QEvent::WhatsThisClicked) {
+        event->accept();
+        QWhatsThisClickedEvent* whatsThisEvent = dynamic_cast<QWhatsThisClickedEvent*>(event);
+        QDesktopServices::openUrl(QUrl(whatsThisEvent->href()));
+        return true;
+    }
+    return false;
+}
+
 DolphinMainWindow::UndoUiInterface::UndoUiInterface() :
     KIO::FileUndoManager::UiInterface()
 {