tiling: When tiling at the end of a grab, use the initial position

and size from when the grab began instead of it's last position
before tiling.

When dragging a window to a tiled state, the final position could
be off the screen depending on the size of the window and the
anchor (grip) position from the start of the grab. If the window
was un-tiled later via keyboard shortcut, the window could return
to its original size, but its position would be incorrect, and
probably up against the edge of the workarea.

This is related to the previous commit (d30b0b0) (similar
symptom, different cause).

Author: mtwebster

src/core/display.c

@@ -2026,6 +2026,7 @@ meta_display_end_grab_op (MetaDisplay *display,
   display->grab_window = NULL;
   display->grab_tile_mode = META_TILE_NONE;
   display->grab_tile_monitor_number = -1;
+  memset(&display->grab_initial_window_pos, 0, sizeof(MetaRectangle));
 
   meta_display_update_cursor (display);
 

src/core/window.c

@@ -3428,7 +3428,20 @@ meta_window_tile (MetaWindow   *window,
   else
     directions = META_MAXIMIZE_VERTICAL;
 
-  meta_window_maximize_internal (window, directions, was_already_tiled ? &window->saved_rect : NULL);
+
+  GdkRectangle *maybe_saved_rect = NULL;
+
+  if (window->display->grab_op != META_GRAB_OP_NONE)
+    {
+      maybe_saved_rect = &window->display->grab_initial_window_pos;
+    }
+  else
+  if (was_already_tiled)
+    {
+      maybe_saved_rect = &window->saved_rect;
+    }
+
+  meta_window_maximize_internal (window, directions, maybe_saved_rect);
   meta_display_update_tile_preview (window->display, FALSE);
 
   /* Setup the edge constraints */