Normally, pressing 'esc' key when the applications menu is displayed, closes the popup and deactivates the plugin button. However, when the user presses 'esc' key while the pointer is above a *submenu* all the popup menus get closed but the plugin button stays active.
Not sure, but this might be because selection-done is not triggered when an escape is pressed. Possibly related to bug #8472.
Fixed in be76d74.