An AbstractDragTarget is introduced. This contains either the DataDevice we are
dragging to or an Xwl bridge.
We set this on Seat along with the active surface.
In future this also allows getting rid of the move filter.
According to the spec, enter has to be send before position.
Sending position first seems to confuse clients, before this
change X windows only seemed to get data when the pointer left and
entered them for a second time. Now it works straight away.
BUG:437406
kwayland-server was updated to follow the result of whether the data
offer was accepted before calling drop.
Our bridge was not updated.
We don't have enough data to know which mimeType the XWayland client
actually has accepted, as that doesn't exist at an X11 level, but it
doesn't have a big actual impact. Despite which mime type gets accepted
any mimetype can be retrieved in the drop event.
Tested against "dropsite" from QtBase widget examples forced into xcb
mode using dolphin as a source.
BUG: 437406
Once in a while, we receive complaints from other fellow KDE developers
about the file organization of kwin. This change addresses some of those
complaints by moving all of source code in a separate directory, src/,
thus making the project structure more traditional. Things such as tests
are kept in their own toplevel directories.
This change may wreak havoc on merge requests that add new files to kwin,
but if a patch modifies an already existing file, git should be smart
enough to figure out that the file has been relocated.
We may potentially split the src/ directory further to make navigating
the source code easier, but hopefully this is good enough already.
