Created attachment 4719
Screenshot showing the unnice borders (especially in the corners) when hovering over it
When having themes with thick borders when hovering over a notification, the outer half of the border is clipped. This leads to suboptimal corners (see attached screenshot).
At least this is the experience on my machine (version 0.2.2 on LMDE and git master) ...
Attached you will also find a patch that fixes this problem. The idea behind it is to not start the background path totally at the edges of the drawing area, but have a padding that is exactly half of the border-width. This way when the border is drawn with cairo_stroke on the background path, it will all fit in the drawing area. By doing this, the close button also has to be moved away from the corner by the same amount.
Please consider the patch more as a general idea on how one could fix this. There is some duplicated code for calculating the padding in xfce_notify_window_ensure_bg_path and xfce_notify_window_expose. This probably should be held as a variable inside the XfceNotifyWindow struct (as well as border-width).
Created attachment 4720
Patches the background path by calculating the correct padding from the edges of the drawing area
Thanks a lot for your contribution, I applied your patch in the git master branch.
I don't think it's necessary to add the padding value to the XfceNotifyWindow object, it's easy to compute and to understand as is.