SeatInterface currently has a separation of kwin's focus scope to
pointer input with early return guards in notifyPointerEnter and
notifyPointerLeave where clients don't get pointer events.
However we don't update the initial state when a drag is started, this
patch notifies sends a pointer leave to the new drag target before the
data_device enter so things are consistent.
This also brings it in line with Weston and Mutter.
notifyPointerLeave has it's early return removed as for wayland windows
as we know nothing will have pointer focus.
The wayland spec is not quite clear about the transforms, but the buffer
transform indicates a transform from wl_surface to wl_buffer or compositor
global coordinate space to composited buffer.
On the other hand, SurfaceItem assumes that the order is vice versa.
libkwineffects was introduced when kwin used to be an executable. It
provided an api to implement effects and shielded from the technical
quirks in kwin.
Over the time, kwin internals had been split and abstractions were
refactored so they can be consumed in scripts or plugins. Besides that,
new ways to implement extensions have been introduced, which use
kwin's internal abstractions.
On the other hand, effects continue using libkwineffects specific apis.
This has a few issues: qtquick effects use both apis and it bites us,
duplicating same apis.
The best solution so far is to merge libkwineffects with libkwin, and
replace libkwineffects abstractions with libkwin abstractions, e.g.
EffectScreen -> Output, etc. This change takes care of adjusting libs.
Obviously, the main disadvantage of doing so is that binary effects
have to be recompiled every time new libkwin is released. But it's
already the case with libkwineffects too.
