Extra padding for xfwm to assist resizing

[philipzae]

Xfce has an issue with resizing, as the resize icon will only appear when it touches the pixels of the window border. Presently that means it will only appear when touching the 2 pixels found on the left, right and bottom parts of the window. Please increase the size to 5 pixels, with the additional 3 pixels taking the color of the internal window background.

You can see how this is done in the Default-hdpi window manager theme compared to the Default theme.