For external plugins (ie : Orage) : tooltips are displayed at the "right - back" of the screen. They should be displayed near the panel when the plugin is hoovered with the mouse (like internal plugins, ie : Application menu).
Bug noticed on latest GIT
Bug also noticed in other applications (ie xfce4-settings), so this bug is probably related to xfce4ui or another shared lib?
Related to Gtk.
yes, I guess, but it began at the same time I moved from xfce 4.8 to 4.10 GIT. Maybe a coincidence JP
Not a coincidence : was caused by bugous DPI setting set by xfsettingsd fixed with http://git.xfce.org/xfce/xfce4-settings/commit/?id=e49a92ae46fb9451d8d8a9c0eb1339d3c62d254d
Funny that a single line can cause so many different bugs.