take a look at the alt-tab handling in sdlmain.cpp
It contains the info you need

Qbix wrote:

take a look at the alt-tab handling in sdlmain.cpp
It contains the info you need

1case SDL_KEYDOWN:
2		case SDL_KEYUP:
3			// ignore event alt+tab
4			if (event.key.keysym.sym==SDLK_LALT) sdl.laltstate = event.key.type;
5			if (event.key.keysym.sym==SDLK_RALT) sdl.raltstate = event.key.type;
6			if (((event.key.keysym.sym==SDLK_TAB)) &&
7				((sdl.laltstate==SDL_KEYDOWN) || (sdl.raltstate==SDL_KEYDOWN))) break;

Thank you! I think you're telling me that I can adapt this so that if SDL_KEYDOWN is true, I should generate an event that acts as if the key is now up, but that may be the stupidest possible interpretation.

I may almost be able to figure out how to code this myself, and I suppose I should do the same with SDLK_LCTRL, SDLK_LSHIFT, etc.

Thank you again - but if anyone can provide any further pointers on how to do this, I'd be very grateful.

Maybe Add the release codes to the keyboard buffer.

Qbix wrote:

Maybe Add the release codes to the keyboard buffer.

Presumably like this:

1/* Now poke a "release ALT" command into the keyboard buffer
2								 * we have to do this, otherwise ALT will 'stick' and cause
3								 * problems with the app running in the DOSBox.
4								 */
5								KEYBOARD_AddKey(KBD_leftalt, false);
6								KEYBOARD_AddKey(KBD_rightalt, false);

That really does tell me almost everything I need to know, I think. Thank you again!

But don't underestimate my ignorance. I'll probably be back for more help before I'm done, unfortunately.

I'm not at the machine I build on, so I won't be able to test this until later, but I wonder if this looks more or less like what I should be doing. It's for sdl_mapper.cpp:

1static void ClearShiftStates(bool pressed) {
2	if (!pressed)
3	return;
4	KEYBOARD_AddKey(KBD_leftalt, false);
5	KEYBOARD_AddKey(KBD_rightalt, false);
6	KEYBOARD_AddKey(KBD_leftctrl, false);
7	KEYBOARD_AddKey(KBD_rightctrl, false);
8	KEYBOARD_AddKey(KBD_leftshift, false);
9	KEYBOARD_AddKey(KBD_rightshift, false);
10	// KEYBOARD_AddKey(KBD_capslock, false); // EDIT - this shouldn't be here
11}

and, near the foot of the file:

1	MAPPER_AddHandler(&ClearShiftStates,MK_f6,MMOD1|MMOD2,"unshift","Clear Shifts");

Apologies for time-wasting if this is merely foolish and ignorant.

EDIT: Well, I built this with the line that cleared CapsLock, and that had the unfortunate effect of turning CapsLock ON when it was already off. So I'm going to try again without the line about CapsLock and will report back if it works correctly when shift states seemed to be locked.

I edited this message because, at first, I reported that the patch worked perfectly, but that was before I realized that I shouldn't have included capslock in the code. Meanwhile, thank you for showing me how to do this!

Yes, the code above does work when shift states get locked in an application. Thanks again to Qbix for showing how to do this!

My DOSbox SVN randomly reverses Shift/Caps Lock. It sounds like what's described here. Have any of the recent builds incorporated these suggested changes?