ui: erase "isHovered" ActionButton state when it is hidden

Button stucks in "hovered" mode, if click on it causes active Toolwindow
tab to change (thus, hiding the toolbar with this button).
Or if active tab is changed by hotkey press while button is being hovered.

(cherry picked from commit ad8171a577)

platform/platform-impl/src/com/intellij/openapi/actionSystem/impl/ActionButton.java

@@ -204,6 +204,8 @@ public class ActionButton extends JComponent implements ActionButtonComponent, A
       myPresentation.removePropertyChangeListener(myPresentationListener);
       myPresentationListener = null;
     }
+    myRollover = false;
+    myMouseDown = false;
     super.removeNotify();
   }