Snap windows to edge with the mouse

[clemens <clemens lab21 org>]

hi all, 

As said in the subject this is about snapping windows to the left/right
edge of the screen with the mouse.
I have developed an extension (put window) which allows you to move and
resize windows using /apps/metacity/window_keybindings. I use a a resize
function that looks like to manipulate the windows:

_resize = function(win, x, y, width, height) {
    win.resize(true, width, height, true);
    win.move(true, x, y);
}

Where win is a reference to global.display.focus_window.


After a window was snapped to an edge with the mouse it is not possible
to move or resize it with the above code. 
Ok thats not absolutely true. After snapping a window to the right edge
open lg an try the following code. It manipulates the window but not in
the expected way: 

 global.display.focus_window.maximize(Meta.MaximizeFlags.HORIZONTAL)
  * changes the height and the y position of the window. 

 global.display.focus_window.resize(true, 400, 400, true);
  * changes the height
  * win.width will not changed because it is maximized horizontal 

 global.display.focus_window.move(true, 200, 200);
  * changes win.y correctly
  * win.x will not changed because it is maximized horizontal

If you call unmaximize the window is restored to the snapped position.
(both statements have this effect)
 global.display.focus_window.unmaximize(Meta.MaximizeFlags.HORIZONTAL);
 global.display.focus_window.unmaximize(Meta.MaximizeFlags.VERTICAL);


This behaviour is not expected but i don't thing it is a bug. I thing
this just happens because i use it the wrong way. 




Another thing i have noticed is that the window changes a little bit
(take right edge again): 
1) the round edge on the left top and bottom corner disappear. 
 * really nice!. If you just "vertical maximize" the window 
   the corners are not changed. 
 * I guess this is done by the snap function. But how? 

2) Resizing
 + "global.display.focus_window.resizeable" returnes true
 + It is possible to resize the window with the keyboard
   +mouse combination (for me its <Super>Mouse_3
 - It is not possible to enter the "resize mode" (right click the header
   -> resize, keyboardbinding)


When I started to develop my extension i used the "snap feature" very
frequently and run into this problem. I checked the gnome-shell and
metacity sources but haven't found anything that really helped me. Now
some other people are using this extension too and a bug is a bug :).

Can someone give me a hint where i can find the "snap function"? 
Or even better, how i can check if a window is snapped and how to
"unsnap" it?

kind regards