Remember the override cursor in GUI::Window and avoid sending a message
to WindowServer when possible.
This removes a lot of synchronous IPC between Browser and WindowServer,
which noticeably improves DOM event responsiveness. :^)
Previously the focused widget would only get cleared on replacement or
on destruction (being a WeakPtr and all.) This could lead to window
dispatching events to a focused widget after it had been removed from
the window's widget tree.
The same issue existed for the hovered widget, etc. So this patch
makes sure that we eagerly clear the various widget pointers in Window
immediately when they are removed from the window's widget tree.
This patch adds two new API's:
- WidgetType& GUI::Window::set_main_widget<WidgetType>();
This creates a new main widget for a window, assigns it, and returns
it to you as a WidgetType&.
- LayoutType& GUI::Widget::set_layout<LayoutType>();
Same basic idea, creates a new layout, assigns it, and returns it to
you as a LayoutType&.
Previously it was only possible to change these window attributes when
creating a new window. This patch adds an IPC message that allows you
to change them at runtime.
We were not repainting windows that were occluded at the time of the
theme changing. This patch adds a way to bypass occlusion testing when
invalidating window rects.
Fixes#1249.
