We want to make events readonly, so stop translating
their coordinates and instead pass the translated
coordinates separately, when propagating events.

Events of type GDK_NOTHING are good for nothing.

Use gdk_event_ref/unref instead of g_object_ref/unref.
Events will stop being object soon.

No backend is emitting GDK_DESTROY events anymore, so no
need to carry this around.

We don't have child windows anymore, so there is no difference.

Use the new event constructors when generating events
for emulating presses.

At the same time, stop setting child_surface in
crossing events. Nothing in GTK looks at it.

Closes #1013

Instead of a fake one where we add .menu to a normal popover. This makes
the menu look like other context menus.

Otherwise it doesn't know what to do with its child widget.

This is triggered by typing / or hitting Ctrl+L. Since we don't have a
visual indicator for this mode right now anyway, the reason for not
allowing it in recent mode cited in the comment just above the
early-exit is irrelevant.

Closes #2178

Unused.

Everything is automatically redrawn when changing the value, etc.

We add the .menu css class to the popover main node, not its contents
node.

This brings us closer to the old GtkMenuItem behavior and also makes
more sense.

Replace the gdk_surface_move_to_rect() API with a new GdkSurface
method called gdk_surface_present_popup() taking a new GdkPopupLayout
object describing how they should be laid out on screen.

The layout properties provided are the same as the ones used with
gdk_surface_move_to_rect(), except they are now set up using
GdkPopupLayout.

Calling gdk_surface_present_popup() will either show the popup at the
position described using the popup layout object and a new unconstrained
size, or reposition it accordingly.

In some situations, such as when a popup is set to autohide, presenting
may immediately fail, in case the grab was not granted by the display
server.

After a successful present, the result of the layout can be queried
using the following methods:

 * gdk_surface_get_position() - to get the position relative to its
   parent
 * gdk_surface_get_width() - to get the current width
 * gdk_surface_get_height() - to get the current height
 * gdk_surface_get_rect_anchor() - to get the anchor point on the anchor
   rectangle the popup was effectively positioned against given
   constraints defined by the environment and the layout rules provided
   via GdkPopupLayout.
 * gdk_surface_get_surface_anchor() - the same as the one above but for
   the surface anchor.

A new signal replaces the old "moved-to-rect" one -
"popup-layout-changed". However, it is only intended to be emitted when
the layout changes implicitly by the windowing system, for example if
the monitor resolution changed, or the parent window moved.

Changing the autohide property means the popover needs to be remapped.
Remapping may need user interaction, so lets just unrealize the popover
if the property changes, forcing the application to remap it should it
be shown again.

Add properties, and use string arrays instead of lists.

Among other things, this renames gtk_icon_theme_list_icons
to gtk_icon_theme_get_icon_names.

Fixes: #2410

Otherwise we lose debug prints from all code that allows NULL displays.

By running it in the capture phase, it will not be starved for events by
the button's click source and make drags actually start a color drag
operation.

No more shooting pointers through pipes

Actually use GValues for the DND operation instead of sending GBytes of
pointer addresses through pipes.

This is a bit complicated because we need to special-case rootwindow
drops, because they're handled on the source side, so we need a custom
ContentProvider.

This removes excess code from the tab dnd machinery

NULL means we don't do content formats checks and accept everything.

We use this for notebook arrows or expanders that react to ongoing
drags.

Enter the Emoji inseration in the undo history.
Also, stop stashing away the selection when we
pop up the Emoji chooser, and use the selection
as-is when we insert the Emoji.

Because you don't. And never did.