a pesky bug

[blakem@world.std.com (Blake Meike)]

Laura Bagnall, here at TERC, has tracked down
another annoying bug down in the innards of
MCL 2.0(p3).  Any of you that have been using
windoids may want to take a look at this

There is a bug with windoids in which *windoid-count*
isn't properly maintained.  Specifically, if you create
a windoid in which there are no other windoids, hide it,
then show it again, then *windoid-count* is 2 instead
of 1 (see transcript below).  This is a problem because
(window-show <window>) seems to do a (set-window-layer 
*windoid-count*) which will then put the window in the
wrong layer.  I defined an :after method for window-show
which works around the problem and seems to make everything
behave correctly (again see transcript), but I'm sure that
there'd be a better fix if one had the source.

? *windoid-count*  ; no windoids around
0
? (setf test (make-instance 'windoid))
#<WINDOID "Untitled" #x6698D9>
? *windoid-count*  ; we've just created and shown one windoid.
1
? (window-hide test)
0
? *windoid-count*  ; no windoids visible.
0
? (window-show test)
2
? *windoid-count*  ;Whoops!  Only one visible windoid, but count is 2!
2
? (window-hide test)
1
? *windoid-count* ;no visible windoids, but count is 1.
1
? (windows :class 'windoid) ;just to confirm that there
			    ;are no visible windoids.
NIL
? (setf *windoid-count* 0)  ;set *windoid-count* to be the correct value again.
0
? (defmethod window-show :after ((w windoid))  ;define patch to work
					       ;around the bug.
     (setf *windoid-count* (length (windows :class 'windoid))))
#<STANDARD-METHOD WINDOW-SHOW :AFTER (WINDOID)>
? (setf test2 (make-instance 'windoid))  ;make another windoid
#<WINDOID "Untitled" #x681A31>
? *windoid-count*  ;one windoid is visible.
1
? (window-hide test2)  ;no windoids are visible.
0
? *windoid-count*
0
? (window-show test2)  ;one windoid is visible.
2
? *windoid-count*  ;and *windoid-count* now reflects this.
1
? 


Blake Meike
TERC
2067 Mass. Ave.
Cambridge, MA  02140