ui: document non-qapi parser cases.

Add comments to the cases not (yet) switched
over to parse_display_qapi().

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 20180507095539.19584-5-kraxel@redhat.com

vl.c

@@ -2114,6 +2114,16 @@ static void parse_display(const char *p)
     const char *opts;
 
     if (strstart(p, "sdl", &opts)) {
+        /*
+         * sdl DisplayType needs hand-crafted parser instead of
+         * parse_display_qapi() due to some options not in
+         * DisplayOptions, specifically:
+         *   - frame
+         *     Already deprecated.
+         *   - ctrl_grab + alt_grab
+         *     Not clear yet what happens to them long-term.  Should
+         *     replaced by something better or deprecated and dropped.
+         */
         dpy.type = DISPLAY_TYPE_SDL;
         while (*opts) {
             const char *nextopt;
@@ -2179,6 +2189,10 @@ static void parse_display(const char *p)
             opts = nextopt;
         }
     } else if (strstart(p, "vnc", &opts)) {
+        /*
+         * vnc isn't a (local) DisplayType but a protocol for remote
+         * display access.
+         */
         if (*opts == '=') {
             vnc_parse(opts + 1, &error_fatal);
         } else {