Make GtkMessageDialog draggable when possible
Currently, GtkMessageDialogs tend to "lock" parent windows from being dragged even when their contents are not selectable. The only way in these cases to drag the windows is by using the keybinding for Mutter "move window". This gets particularly serious when the dialogs are not immediately dismissable (e.g. when they indicate an ongoing operation, with only a "cancel" button - see some edge cases in Nautilus with gvfs as example).
For the sake of UX cleanliness, I would tend to suggest they could be made draggable in general as a rule, in a HeaderBar-like fashion, but have not explored in detail long-term implications and side effects this would bring.
Edited by Raffaele