Re: make-pointer-invisible on Windows

[Eli Zaretskii <eliz@gnu.org>]

> Date: Mon, 29 Jun 2015 11:45:49 +0200
> From: martin rudalics <rudalics@gmx.at>
> CC: emacs-devel@gnu.org
> 
>  > No mystery here, it turns out.  On XP, we get the WM_ERASEBKGND
>  > message when (portions of) the Emacs frame previously covered by other
>  > windows are uncovered.  In response, we erase the rectangle specified
>  > by the message, and we do that from the input thread, i.e. this works
>  > even if the main thread is busy.
> 
> I don't think it's worth changing this but in principle we could erase
> from the main thread as well?

We could, but that brings the difficulty I mentioned below, with
collecting several such redraws of different rectangles, and
repainting them all at once.  Not rocket science, but needs some work.

> That is, erasing without painting doesn't make much sense anyway.

Maybe, I really know nothing about this.

>  > On Windows 7, neither WM_ERASEBKGND nor WM_PAINT are sent, except when
>  > the Emacs frame is moved or resized.  So we don't erase the rectangle,
>  > and the text remains on screen.
> 
> So you do get a blank rectangle when you (de-)maximze the frame I
> suppose.

Of course.