win16 target: win 3.0 real mode bug?

[ghost]

When trying following win16 example, after compiling with latest OW, the following win 3.0 problem occurs.

https://github.com/TransmissionZero/Win16-Example-Application

`The Open Watcom build of the application doesn't work correctly under Windows 3.0 when running in Real Mode. The application will start but the menu is missing and the about dialog won't display. I've found Open Watcom to be a bit hit and miss, where certain seemingly harmless changes of compiler option result in an application which crashes, so it may be possible to fix this by changing the compiler options. It runs fine under Windows 3.0 in Standard Mode and 386 Enhanced Mode.

The Open Watcom build of the application has optimisations switched off. With optimisations enabled, the application crashes on startup.`

[jmalak]

I am not much familiar with Windows 3.0 real-mode, but probably full fat Windows prolog/epilog is necessary, option -zw (cases are important). Also there can be some assumption about segment attributes as fixed or movable etc. Next problem could be resources, resource compiler need to use -30 option and some other switch. I don't test OW for such target that I can not guarantee anything. I am not sure if there are some limitation in version to Windows 3.10 and above for default setup.

[joncampbell123]

One important thing to know about real-mode Windows is that segments are movable, and therefore if you have a FAR pointer to anything, that FAR pointer will at some point become invalid when Windows moves segments and compacts memory.

One possible quick way to overcome that might be to call LockSegment(-1) at the top of the WinMain() function as a hack.

[joncampbell123]

As for resources, Windows in real-mode will not load resources unless you declare them MOVEABLE and DISCARDABLE because of real-mode memory management limitations.

Consider this example in DOSLIB which compiles all the way down to Windows 1.0:

https://github.com/joncampbell123/doslib/tree/master/windows/exmenus