Thanks for looking at this Claus.
no problem - I'm kind of nearby, and I'm not promising anything (unless just looking at it is going to help;-).
- the full-screen titlebar effect with the SOE variant suggests some window-handling incompatibility, if it wasn't for Hugs and GHC using the same graphics source code.. (is there a difference in the win32 bindings for Hugs vs GHC?)
[This mail got rather long. My best guess is that yield on GHC doesn't yield as thoroughly as on Hugs and that the Win32 library isn't being greencarded with the --safe-code flag. (Either by itself would probably be fine, it's having both at once that is probably killing you.)]
According to the docs, yield does as yield should, and the unix version (ghc/hgl/X) seems to work.. Btw, while looking at code with scheduling-related issues in mind, other questions appeared to me: Shouldn't all those IORefs (e.g., for the list of windows) be MVars in the GHC version? For a start, what about NoInline pragmas for global IORefs? But, at least on unix, these don't seem to be the problem.. Unless there are any other suggestions, I could give the green card --safe-code a try. But why doesn't the green card input use %safecode to eliminate that potential error source?-) And how would cross-ffi garbage-collection issues affect window parameters at startup? Anyway, is there a useable win32 green card input package hanging around somewhere (the link to glasgow is dead it seems; CVS has moved the gc-sources aside and has never been very modular - is there a way for me to take the win32/gc-src/ directory from CVS and make it, without having to prepare the various other parts of fptools that fptools-Makefiles tend to depend on so merrily?-(. Alternatively, is anyone out there using ghc's win32 binding? Presumably, that kind of problem would show up in other uses. Claus PS. Is there a way to get system call traces on windows/cygwin?