Okay, I've spent a whole day on this now, and it finally kinda works!
With this patch, CObject and all of its derived classes are reference
counted instead of tree-owned.
The previous, Qt-like model was nice and familiar, but ultimately also
outdated and difficult to reason about.
CObject-derived types should now be stored in RefPtr/NonnullRefPtr and
each class can be constructed using the forwarding construct() helper:
auto widget = GWidget::construct(parent_widget);
Note that construct() simply forwards all arguments to an existing
constructor. It is inserted into each class by the C_OBJECT macro,
see CObject.h to understand how that works.
CObject::delete_later() disappears in this patch, as there is no longer
a single logical owner of a CObject.
With this patch, CEvents no longer stop at the target object, but will
bubble up the ancestor chain as long as CEvent::is_accepted() is false.
To the set accepted flag, call CEvent::accept().
To clear the accepted flag, call CEvent::ignore().
Events start out in the accepted state, so if you want them to bubble
up, you have to call ignore() on them.
Using this mechanism, we now ignore non-tabbing keydown events in
GWidget, causing them to bubble up through the widget's ancestors. :^)
Normally if a GWidget has the is_greedy_for_hits() flag set, all hit
tests will hit the widget itself instead of its descendants.
Sometimes it may be desirable to override this behavior, and so this
flag now allows you to do that.
This solves an issue in GScrollableWidget where hiding one of the two
scrollbars needs to trigger a relayout since the other one should grow
into the "shared space" in the bottom right corner.
A GWidget can now override custom_layout() which will be called at any
time we would normally delegate work to the GLayout, e.g on resize
or child visibility changes, size policy changes, etc.
Instead of LibGUI and WindowServer building their own copies of the drawing
and graphics code, let's it in a separate LibDraw library.
This avoids building the code twice, and will encourage better separation
of concerns. :^)
