X position relative to src_widget
Y position relative to src_widget
location to store X position relative to dest_widget
location to store Y position relative to dest_widget
FALSE if either widget was not realized, or there was no common ancestor. In this case, nothing is stored in *dest_x and *dest_y. Otherwise TRUE.
Translate coordinates relative to src_widget’s allocation to coordinates relative to dest_widget’s allocations. In order to perform this operation, both widgets must be realized, and must share a common toplevel.