provide focus follows mouse for widgets in the main window (bug #59701) * gui-preferences-dw.h: new preference for the new feature * octave-dock-widget.cc (octave_dock_widget): initialize new class variable; (handle_settings): get preference for new feature from settings file and store it in new class variable (eventFilter): catch mouse enter event and activate widget if widget is docked and feature is enabled * octave-dock-widget.h: new class variable m_focus_follows_mouse * settings-dialog.cc (settings_dialog): set related check box depending on preference from settings file; (write_changed_settings): write check box state into settings file * settings-dialog.ui: add checkbos for new feature with tool tip

--- a/libgui/src/gui-preferences-dw.h	Sat Dec 19 16:29:32 2020 +0100
+++ b/libgui/src/gui-preferences-dw.h	Sun Dec 20 12:06:59 2020 +0100
@@ -29,6 +29,9 @@
 #include "gui-preferences.h"
 
 const gui_pref
+dw_focus_follows_mouse ("DockWidgets/focus_follows_mouse", QVariant (false));
+
+const gui_pref
 dw_title_custom_style ("DockWidgets/widget_title_custom_style",
                        QVariant (false));