guido@cwi.nl (Guido van Rossum) (09/27/90)
[I have no idea where to mail this (nor does our local SGI guru) so I'll post it here and hope someone at SGI will pick it up.] The 3.3 Xsgi is definitely a vast improvement, but I once crashed it and got it to behave weird with this bug: I have a program (really a library -- stdwin if you're interested) which creates a tall window, say, 100x500, with an even taller subwindow, say, 100x2000. Using scroll bars I move the subwindow up and down in the main window and draw in it (in the subwindow, that it). This goes fine. But I want to invert a particular line of text. This I do with XOR drawing mode and the bitplane set to the XOR of the foreground and background pixel values (I draw B/W only). When the XORed rectangle is visible in the main window, it is fine. When I scroll it a little bit out of sight, it is still fine. But when I scroll it way out of sight (outside the screen boundaries?), the entire main window gets inverted. This is consistent; when I issue the same XOR instruction again the window is inverted back to normal. Note that if I make the width of the inverted rectangle much larger than the window (1000) I may crash the X or NeWS server (this happened the first time when I tried it). I suspect that the outcome of the clipping applied by the server is wrong, but I can only guess. I can provide an example if required. -- Guido van Rossum, Centre for Mathematics and Computer Science (CWI), Amsterdam guido@cwi.nl or ..!hp4nl!cwi.nl!guido or guido%cwi.nl@uunet.uu.net ZZ Q q :q :wq :q! :w! :-)