Like it says on the tin. It occurred to me after fixing xshape (#501) and running virtualbox that we can fairly easily do a seamless mode for win32 by sending the list of window geometries as a list of xshape rectangles.
The more tricky part is going to be the screen size issues.. we should resize the "server" screen to the size of the client, which may not be possible. So maybe we have to resort to some sort of clipping.
Partial support added in r9697, the window still has decorations which allows us to avoid the issues with screen sizes. A good start.
Changing the resolution on win32 does not look too hard: msdn: ChangeDisplaySettings
EDIT: this is what this looks like at present when connecting with a trunk Linux client to a trunk win32 server started with:
SET XPRA_WIN32_SEAMLESS=1 xpra_cmd shadow :0 --bind-tcp=0.0.0.0:10000
(top left is the transparent window holding the same windows as the bottom right window, which is a virtualbox XP virtual machine)
win32 semi-seamless server
Changing video mode using rotate monitor.
But we can only set existing modes, not create new ones (similar to the limitations we have with Xdummy), and I cannot see a way to tell win32 to ignore part of the screen... so this isn't going to help much.
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/897