I recently updated xfdashboard in (rawhide and) Fedora 24 to version 0.5.90. Apart from several under the hood changes, xfdashboard 0.5.90 introduces the hot corner plugin.
Screenshot below -
The activation corner can be set to any of the four corners of the screen while radius of activation was fun to play with. I preferred a slightly bigger radius but that's, of course, a personal preference.