Looking for ideas to fix x2x in rootless mode...

[Thomas Chadwick]

I'm hoping some folks on the ML might help me brainstorm a solution to 
fixing x2x in rootless mode...

For those of you not familiar with x2x, it's a handy utility that gives you 
a dual-headed X display if you have side-by-side workstations both running X 
(one is designated the "from" display, the other the "to" display).  It does 
this by simply grabbing the pointer and keyboard focus on the "from" 
display, and generating fake pointer and keyboard events on the "to" display 
whenever it receives pointer or keyboard events from the "from" display.

In my particular case, the "from" display is a PC running Cygwin/XFree86, 
and the "to" display is an RS/6000 Workstation.

The trouble with rootless mode is that when my pointer leaves the X server 
region, x2x no longer gets any pointer events from the "from" display.  This 
has the effect of restricting my pointer movements on the "to" display to 
areas that are occupied by X clients on the "from" display.

I tried patching x2x by using the Windows API calls SetCapture(HWND hwnd) 
and ReleaseCapture() at the same time x2x does XGrabPointer() and 
XUnGrabPointer() respectively.  However, the Capture fails.  If I interpret 
the MSDN documentation correctly, I think it's because the x2x.exe thread 
does not own the HWND it's trying to do the Capture on (XWin.exe does).  I 
suppose I could try to overcome this by patching the XGrabPointer() and 
XUnGrabPointer() functions in the XFree86 source directly.  This would 
result in XWin doing the SetCapture as a result of calling XGrabPointer() 
from x2x.

I haven't actually tried this, however, because it occurs to me that I have 
an additional problem.  Again, if I interpret the scant documentation 
properly, it looks to me that while SetCapture may grab the pointer, 
clicking a mouse button while outside the X server region will cause the 
capture to be released and the mouse button event to go to whatever MS 
Windows client is under the pointer at the time of the click.  This would 
have the effect of letting me point to any region in the "to" display as 
long as I don't press a mouse button.  Not very useful.

Perhaps there is a different API call which keeps a "stronger" hold of the 
pointer than SetCapture()?

How about calling XWarpPointer() from x2x to keep the pointer from leaving 
the X server region?

Any other ideas?


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