input: don't deliver mouse events if mouse area is not set

This caused the OSC to be always visible at startup on X11:
- EnterNotify event send a mouse event to input.c
- OSC has not completely initialized yet, and no mouse area is set
- mouse event is dispatched to "showhide" OSC section
- OSC becomes visible, regardless of mouse position

Fix this by treating the mouse area as empty if it's not set, instead of
infinite as it was before this commit. This means an input section must
set a mouse area to receive mouse events at all. We also have to change
the default section to receive mouse events with the new behavior.

Also, if MOUSE_MOVE is unmapped (or mapped to something that doesn't
parse), and produces no command, the mouse position wouldn't be updated
(because the mouse position is bound to input commands), so we have to
generate a dummy command in this case.

(This matters only for the OSC, On Screen Controller, which isn't merged
yet, so these changes shouldn't have much effect right now.)

mpvcore/input/input.c

@@ -1343,8 +1343,9 @@ static struct cmd_bind *find_any_bind_for_key(struct input_ctx *ictx,
         struct cmd_bind *bind = find_bind_for_key_section(ictx, s->name, n, keys);
         if (bind) {
             struct cmd_bind_section *bs = bind->owner;
-            if (!use_mouse || !bs->mouse_area_set ||
-                test_rect(&bs->mouse_area, ictx->mouse_vo_x, ictx->mouse_vo_y))
+            if (!use_mouse || (bs->mouse_area_set && test_rect(&bs->mouse_area,
+                                                               ictx->mouse_vo_x,
+                                                               ictx->mouse_vo_y)))
                 return bind;
         }
         if (s->flags & MP_INPUT_EXCLUSIVE)
@@ -1668,6 +1669,8 @@ void mp_input_set_mouse_pos(struct input_ctx *ictx, int x, int y)
     update_mouse_section(ictx);
     struct mp_cmd *cmd =
         get_cmd_from_keys(ictx, NULL, 1, (int[]){MP_KEY_MOUSE_MOVE});
+    if (!cmd)
+        cmd = mp_input_parse_cmd(bstr0("ignore"), "<internal>");
 
     if (cmd) {
         cmd->mouse_move = true;
@@ -2185,7 +2188,7 @@ static bool test_mouse(struct input_ctx *ictx, int x, int y, int rej_flags)
 
 bool mp_input_test_mouse_active(struct input_ctx *ictx, int x, int y)
 {
-    return test_mouse(ictx, x, y, 0);
+    return test_mouse(ictx, x, y, MP_INPUT_ALLOW_HIDE_CURSOR);
 }
 
 bool mp_input_test_dragging(struct input_ctx *ictx, int x, int y)
@@ -2249,7 +2252,10 @@ struct input_ctx *mp_input_init(struct MPOpts *opts)
     pthread_mutexattr_destroy(&attr);
 #endif
 
-    mp_input_enable_section(ictx, NULL, 0);
+    // Setup default section, so that it does nothing.
+    mp_input_enable_section(ictx, NULL, MP_INPUT_ALLOW_VO_DRAGGING |
+                                        MP_INPUT_ALLOW_HIDE_CURSOR);
+    mp_input_set_section_mouse_area(ictx, NULL, INT_MIN, INT_MIN, INT_MAX, INT_MAX);
 
     // "Uncomment" the default key bindings in etc/input.conf and add them.
     // All lines that do not start with '# ' are parsed.

mpvcore/input/input.h

@@ -118,6 +118,8 @@ enum mp_input_section_flags {
     MP_INPUT_EXCLUSIVE = 1,
     // Let mp_input_test_dragging() return true, even if inside the mouse area.
     MP_INPUT_ALLOW_VO_DRAGGING = 2,
+    // Don't force mouse pointer visible, even if inside the mouse area.
+    MP_INPUT_ALLOW_HIDE_CURSOR = 4,
 };
 
 struct input_ctx;