If you drag your mouse according to the attached image, from top to bottom towards the title bar, when the mouse pointer reaches the title bar, window moving is suddenly triggered. Similar thing happens with the window resize corner in the bottom right.
Besides, if you click on the close window button "x" in the upper left corner but release the mouse pointer elsewhere, the "x" button remains highlighted.
I have already committed a fix for the above problems. Actually the fix is based on the changes to check_pos_win() in my viewport patch issued some time ago. With this fix, mouse move events inside windows will be properly handled -- the general idea is to use (mx, my) while handling mouse move events (which do not have originating click position), and to use (cx, cy) for other mouse events like click, drag and release which have originating click positions.