Make the OSARA send context menu in the I/O Routing window expose the checked/unchecked state of toggles such as mute and mono.

This only works in REAPER 7.11 and later, as this information wasn't exposed to MSAA prior to that.
In earlier versions, the checked/unchecked state won't be exposed, as was always previously the case.

Author: jcsteh

src/reaper_osara.cpp

@@ -2546,8 +2546,6 @@ void sendMenu(HWND sendWindow) {
 	HMENU menu = CreatePopupMenu();
 	MENUITEMINFO itemInfo;
 	itemInfo.cbSize = sizeof(MENUITEMINFO);
-	// MIIM_TYPE is deprecated, but win32_utf8 still relies on it.
-	itemInfo.fMask = MIIM_TYPE | MIIM_ID;
 	itemInfo.fType = MFT_STRING;
 	child.vt = VT_I4;
 	int item = 0;
@@ -2556,8 +2554,21 @@ void sendMenu(HWND sendWindow) {
 		VARIANT role;
 		if (acc->get_accRole(child, &role) != S_OK || role.vt != VT_I4)
 			continue;
-		if (role.lVal != ROLE_SYSTEM_PUSHBUTTON && role.lVal != ROLE_SYSTEM_COMBOBOX)
+		// MIIM_TYPE is deprecated, but win32_utf8 still relies on it.
+		itemInfo.fMask = MIIM_TYPE | MIIM_ID;
+		if (role.lVal == ROLE_SYSTEM_CHECKBUTTON) {
+			itemInfo.fMask |= MIIM_STATE;
+			VARIANT state;
+			if (acc->get_accState(child, &state) == S_OK && role.vt == VT_I4 &&
+					state.lVal & STATE_SYSTEM_CHECKED) {
+				itemInfo.fState = MFS_CHECKED;
+			} else {
+				itemInfo.fState = MFS_UNCHECKED;
+			}
+		} else if (role.lVal != ROLE_SYSTEM_PUSHBUTTON &&
+				role.lVal != ROLE_SYSTEM_COMBOBOX) {
 			continue;
+		}
 		BSTR name = NULL;
 		if (acc->get_accName(child, &name) != S_OK || !name)
 			continue;