Function DialogPrep

source/window.cpp:1829–1865

void DialogPrep()
// Having it as a function vs. macro should reduce code size due to expansion of macros inside.
{
	// Make the thread immediately interruptible but don't change g->ThreadIsCritical,
	// since DIALOG_END will refer to it when resetting g->AllowThreadToBeInterrupted.
	g->AllowThreadToBeInterrupted = true;
	if (g_KeybdHook) // Workaround added in v1.1.22.01.
	{
		// If a Control or Shift key is physically down, the dialog somehow recognizes this
		// and acts as though the key is logically down even if it really isn't.  Logically
		// releasing the key before or after the dialog is shown appears to work around the
		// issue.  If one L/R modifier is logically down and the opposite side is physically
		// down, the workaround isn't wanted/needed, because the dialog *should* act like
		// the key is down, and it does so until the key is released.
		// UPDATE: I'm not able to reproduce this problem on Windows 10, but it's done there
		// too just in case.
		mod_type mods_logical = ConvertModifiersLR(g_modifiersLR_logical);
		modLR_type mods_not_to_release = ConvertModifiers(mods_logical & (MOD_CONTROL | MOD_SHIFT))
			| MOD_LALT | MOD_RALT | MOD_LWIN | MOD_RWIN; // v1.1.23.05: No need to release these keys.
		modLR_type mods_to_release = g_modifiersLR_physical & ~mods_not_to_release;
		if (mods_to_release)
		{
			if (mods_logical == MOD_WIN) // Fixed in v1.1.23.05 to exclude combinations like MOD_WIN|MOD_CONTROL, which don't need this.
			{
				// Even though the Win key isn't being released, sending a Shift or Control key-up
				// triggers the Start menu.  To prevent that, we send the mask key.  This has been
				// confirmed to apply to #Control, #Shift and the left/right variants.
				KeyEventMenuMask(KEYDOWNANDUP, KEY_IGNORE_ALL_EXCEPT_MODIFIER);
				// Releasing the Win key now does not prevent it from being "masked" again later:
				//mods_to_release |= (g_modifiersLR_logical & (MOD_LWIN | MOD_RWIN));
			}
			SetModifierLRState(0, mods_to_release, NULL, false, false);
		}
	}
	if (HIWORD(GetQueueStatus(QS_ALLEVENTS))) // See DIALOG_PREP for explanation.
		MsgSleep(-1);
}