Problem with mouse selecting a region

[Neal Becker]

emacs-23.1 (linux).

How to select a region with the mouse that doesn't fit on a single screen?  
This works:
Press mouse1.  Drag off bottom edge, this will cause screen to scroll.  
Release mouse1 when satisfied.

But the scrolling speed when dragging isn't always satisfactory.  Here's 
what should work but doesn't:
Press mouse1.  Drag and release (without moving off bottom edge).  Now a 
region is highlighted.  Let's extend it.

If you click on the left fringe on the _same screen_ the region is extended.  
But, lets scroll down.  Use mousewheel to scroll.  Or, use any other method 
to scroll.  As soon as the screen is redrawn, the original selection is 
lost!  That's serious breakage.  I don't think any other app acts this way.

Again, when scrolling, as long as the selected region is visible, the region 
is still active.  As soon as it scrolls off the screen, it's no longer 
active.  I don't think it should act that way.