ejk@uxh.cso.uiuc.edu (Ed Kubaitis) (02/13/90)
It appears that a viewported list widget (Xaw) runs into trouble when the height of the total list in pixels (taking into account the font in use) exceeds about 32K. For very large fonts (e.g. "*helv*-34-*") there seems to be a limit of about 16K. Attempts to scroll the list beyond that point cause the list to scroll back to the beginning or be truncated prematurely. This has been observed on two clients running X11R4 (Sequent Symmetry and Convex) and on two servers (NCD19 and Visual 14"). Is this a known restriction/limitation or does it sound like a bug that should be reported? If the latter, would someone please tell me where to send the report and support materials (about 100 lines) and whether there is a standard template to use for the report. Thanks ------------------------- Ed Kubaitis (ejk@ux1.cso.uiuc.edu) Computing Services Office - University of Illinois, Urbana
joel@decwrl.dec.com (Joel McCormack) (02/13/90)
You are looking at the fundamental limitation of the protocol to a 16-bit (signed) address space. X and y coordinates are limited to the range [-32768..32767]. A scrolling mechanism can hit this limit rather easily if attempts to hide all scrolling activities by giving the scrollee a huge window in which to paint. The correct way to do things, though not the easiest, is to avoid the use of viewports to accomplish scrolling. - Joel McCormack (decwrl!joel, joel@decwrl.dec.com)