Don't eagerly set wxKeyEvent position fields.

This results in a noticeable delay when using wxGTK via a remote X11
connection for every key event as a round trip to server is needed to get the
mouse pointer position every time a key is pressed or released.

Only provide the position on demand. And explain that it's actually not very
useful as it's simply the same as the current mouse position.

Closes #14361.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72207 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/event.h

@@ -1444,6 +1444,9 @@ public:
     //@{
     /**
         Obtains the position (in client coordinates) at which the key was pressed.
+
+        Notice that this position is simply the current mouse pointer position
+        and has no special relationship to the key event itself.
     */
     wxPoint GetPosition() const;
     void GetPosition(long* x, long* y) const;
@@ -1502,11 +1505,15 @@ public:
 
     /**
         Returns the X position (in client coordinates) of the event.
+
+        @see GetPosition()
     */
     wxCoord GetX() const;
 
     /**
         Returns the Y position (in client coordinates) of the event.
+
+        @see GetPosition()
     */
     wxCoord GetY() const;