The brute force approach is when you click, that suppresses paints for
5 seconds. In paint you just compare now with last click. If less than
5000 ms, you just return.

The catch is the text representation is continuing to change, so your
visuals are out of date. Selecting will select the wrong text.

You actually need to suppress updates.  how about this.
Have two windows.  When the user clicks, you create a clone, and
continue letting it receive updates in the background.  When the user
has finished his thing or there is a timeout, you discard the front
window and replace it with the background one.

But that won't work if the user is updating the window. Because then
her changes will be lost.

So you need to buffer up the changes in some sort of FIFO queue while
she is busy using the screen.  See
http://mindprod.com/jgloss/queue.html