in theory, only the tap event should do all we need, but in reality, we translate the tap event into a mouse left click by keymapping (by xml, no additional info can be added here), and the mouse left click event did do OnMouseOver and focus the control before the click action, but, there's no render between the focus and the click action, so if the click action is an operation a little slow, from ui we can not see the target control is focused, that's not good. so here need an additional mouse motion to focus the control before a render and after render do the real action (by SendAction). so, to finish the focus and render before action, we has to simulate an mouse motion for that.
the confliction is that, the fullscreen window trade the 'pointer position event' (mouse motion) as a trigger of osd display, that's the problem, since we can not change this, so have to accept it and avoid it like this.