titled-dialog: Show min and max buttons (Fixes #26)
Since GtkDialogs with CSD only have a close button and our settings dialogs are only "dialogs" we want to show the min and max buttons too there. This means we have to set the type-hint for the window manager to "normal" and to be sure we also manually center the window on the active screen.
This should work for XfceTitledDialogs created from Glade or via the API.
To test I removed this line: https://gitlab.xfce.org/xfce/xfce4-session/-/blob/master/settings/xfce4-session-settings.ui#L66 and rebuilt the settings dialog.
Please test!