Returns the point halfway between the events' positions.
This assumes that both events have X/Y information. If not, this function returns false.
| event1 |
first `GdkEvent` |
| event2 |
second `GdkEvent` |
| x |
return location for the X coordinate of the center |
| y |
return location for the Y coordinate of the center |
|
true if the center could be calculated. |