The backend is now mature enough to not explode with multiple windows
but the `DisplayServer` API still cannot meet some guarantees required
by the various Wayland protocols we use. To meet those guarantees this
patch adds three new elements to the DisplayServer API, with relative
handling logic for `Window` and `Popup` nodes:
- `WINDOW_EVENT_FORCE_CLOSE`, which tells a window to *forcefully*
close itself and ensure a proper cleanup of its references, as Wayland
enforces this behavior;
- `WINDOW_FLAG_POPUP_WM_HINT`, which explicitly declares a window as a
"popup", as Wayland enforces this distinction and heuristics are not
reliable enough;
- `FEATURE_SELF_FITTING_WINDOWS`, which signals that the compositor can
fit windows to the screen automatically and that nodes should not do
that themselves.
Given the size of this feature, this patch also includes various
`WaylandThread` reworks and fixes including:
- Improvements to frame wait logic, with fixes to various stalls and a
configurable (through a `#define`) timeout amount;
- A proper implementation of `window_can_draw`;
- Complete overhaul of pointer and tablet handling. Now everything is
always accumulated and handled only on each respective `frame` event.
This makes their logic simpler and more robust.
- Better handling of pointer leaving and pointer enter/exit event
sending;
- Keyboard focus tracking;
- More solid window references using IDs instead of raw pointers as
windows can be deleted at any time;
- More aggressive messaging to window nodes to enforce rects imposed by
the compositor.
`Viewport.get_stretch_transform()` returns the automatically computed
2D stretch transform. Combined with `Transform2D.get_scale()`, this is
useful when using the `canvas_items` stretch mode in a project.
There are many situations where knowing this factor is useful:
- Divide Camera2D zoom to keep the size of the 2D game world identical
regardless of the 2D scale factor (so that UI elements can still be scaled).
- Make certain controls always drawn at 1:1 scale
(e.g. for the crosshair in a FPS). This is done by dividing the Control
node's scale by the scale factor.
- Improve documentation related to embedded subwindows and single-window mode.
- Add `minsize` keyword aliases for `popup_centered_clamped()` methods
to ease migration to Godot 4.x (this was Godot 3.x terminology).
This intends to be the correct way to handle non-child windows becoming covered by the current window when becoming focused.
Enabling this property on select windows, they will become transient to the currently focused one when becoming visible.
This deprecates the "unparent_when_invisible" function introduced by #76025.
