spin on GetCurrentButtonState before warping cursor when grabbing cocoa input. this keeps the window from jumping if you click on its titlebar to focus

basis/core-graphics/core-graphics.factor

@@ -116,6 +116,8 @@ FUNCTION: CGError CGAssociateMouseAndMouseCursorPosition ( boolean_t connected )
 
 FUNCTION: CGError CGWarpMouseCursorPosition ( CGPoint newCursorPosition ) ;
 
+FUNCTION: uint GetCurrentButtonState ( ) ;
+
 <PRIVATE
 
 : bitmap-flags ( -- flags )

basis/ui/backend/cocoa/cocoa.factor

@@ -128,6 +128,7 @@ M: cocoa-ui-backend (grab-input) ( handle -- )
     window>> -> frame CGRect>rect rect-center
     NSScreen -> screens 0 -> objectAtIndex: -> frame CGRect-h
     [ drop first ] [ swap second - ] 2bi <CGPoint>
+    [ GetCurrentButtonState zero? not ] [ yield ] while
     CGWarpMouseCursorPosition drop ;
 
 M: cocoa-ui-backend (ungrab-input) ( handle -- )