Right top corner does not click "Close" button in hidpi

It's a standard behavior to do this:
1. Maximize a window
2. Move mouse cursor to the right top most corner
3. Click mouse
4. Expect the "Close" button to be clicked so that windows is closed.

This works as expected with the low dpi version of xfwm4 theme. But with the hidpi xfwm4 theme that top right pixel is not part of the close button but instead part of the window frame. As a result clicking at that location no longer close the windows.

Reproduce the maximized-window behavior described in the issue using the low-DPI and HiDPI xfwm4 themes. Compare the window-frame and Close-button bounds, then verify that clicking the top-right pixel closes the window as it does with the low-DPI theme.

Written by the indexing model from the issue text.