Ensure that wxTestableFrame is shown on the (main) screen.

Undo the accidental commit of local modifications in
13a119cca8 .

This is the backport of 498f07a5b2 from
master.

tests/testableframe.cpp

@@ -18,7 +18,8 @@
 
 wxTestableFrame::wxTestableFrame() : wxFrame(NULL, wxID_ANY, "Test Frame")
 {
-    Move(2000, 200);
+    // Use fixed position to facilitate debugging.
+    Move(200, 200);
 }
 
 void wxTestableFrame::OnEvent(wxEvent& evt)