STR #1153

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STR #1153

Application:FLTK Library
Status:1 - Closed w/Resolution
Priority:4 - High, e.g. key functionality not working
Scope:2 - Specific to an operating system
Subsystem:Core Library
Summary:Runtime Errors with FLTK 1.1.7 on 64-bit native WinXP-x64
Created By:plipa
Assigned To:matt
Fix Version:1.1-current (SVN: v5094)
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Trouble Report Files:

Name/Time/Date Filename/Size top right image
#1 plipa
09:22 Jan 25, 2006
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Trouble Report Comments:

Name/Time/Date Text top right image
#1 plipa
09:22 Jan 25, 2006
MatthiasM suggested I file a bug report:
I tried to run FLTK 1.1.7 on 64-bit windows (running native
WinXP-x64/SP1).  The build with out-of-the-box Cmake settings works fine
without errors. But at runtime, every one of the example apps in
fltk-1.1.7\bin\debug crashes with  an error msg (see attached .gif for a
The debugger stops in sreen_xywh.cxx in function at line
screens[num_screens] = mi.rcWork;


if (num_screens >= 16) return TRUE;


mi.cbSize = sizeof(mi);

// GetMonitorInfo(mon, &mi);

fl_gmi(mon, &mi);

screens[num_screens] = mi.rcWork;

num_screens ++;

return TRUE;


The value for mi.rcWork seems fine:
mi.rcWork: {top=24574296 bottom=270583312 left=24574352 right=2130571264}

Does anyone have experience on x64? Do I need to change some build settings
in CMake?
Note, I am compiling for a 32-bit app (to run both on x64 and be portable to Wintel 32-bit machines). It might be that I am just doing something stupid (due to my inexperience on 64-bit - maybe I missed an obvious compile flag, etc).

Thanks in advance for any info/hint/fix.

Peter Lipa
#2 sebbarre
07:06 Jan 26, 2006
I can see the exact same issue. My guess is that it has nothing to do with your maching being 64 bits (mine is 32). I bet you have two screens, and your are using them in Dual mode (say, nVidia's DualView) to create a single large desktop over your two screens. In my specific case, my screen #2 is actually on the left, my screen #1 is on the right (i.e. I work primarily on my right screen, but I can put some windows on the left one).
Try disable dual view mode and run the example using a desktop over just a single screen: this does not crash for me anymore. Of course, this is definitely not a solution, but at least you can reproduce the problem.
Note that it does not happen if you build the library using the VisualC++ solution file instead of CMake. Since the CMake team is 10 feet from me, I will forward the problem.
#3 matt
19:31 Apr 26, 2006
Did the CMake team come up with a solution on this?

Screen coordinates can actually be negative... .
#4 matt
03:38 May 10, 2006
This is an attempt to fix the described issues when querying multiple monitors on defferntly set up Windows environments. Would the posters please test if the new version works. Thanks.  
#5 matt
03:54 May 10, 2006
If this bug was not resolved, please send a reply mail and I will reopen the issue.  
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