i3 - improved tiling WM

Implement drag cancel for moving floating windows

Patch status: needinfo

Patch by Tony Crisci

Long description:

Hi, I am a new developer and this is my first code submission to a
project. If I do anything wrong, please let me know.

The patches I've submitted implement #1074 "Add ability to escape
out of a mouse-resize operation".

To apply this patch, use:
curl http://cr.i3wm.org/patch/234/raw.patch | git am

b/src/floating.c

18 
@@ -441,8 +441,16 @@ void floating_drag_window(Con *con, const xcb_button_press_event_t *event) {
19 
      * after the user releases the mouse button */
20 
     tree_render();
21
22 
+    /* Store the initial rect in case of user cancel */
23 
+    struct Rect initial_rect = con->rect;
24 
+
25 
     /* Drag the window */
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-    drag_pointer(con, event, XCB_NONE, BORDER_TOP /* irrelevant */, XCURSOR_CURSOR_MOVE, drag_window_callback, event);
27 
+    int drag_result = drag_pointer(con, event, XCB_NONE, BORDER_TOP /* irrelevant */, XCURSOR_CURSOR_MOVE, drag_window_callback, event);
28 
+
29 
+    /* If the user cancelled, undo the changes. */
30 
+    if (drag_result == 1) {
31 
+        floating_reposition(con, initial_rect);
32 
+    }
33
34 
     /* If this is a scratchpad window, don't auto center it from now on. */
35 
     if (con->scratchpad_state == SCRATCHPAD_FRESH)