x11: when using --wid, inherit event flags from parent window

When embedding a X window, it's hard to control whether it receives
mouse/keyboard input or not. It seems the X protocol itself makes this
hard (basically due to the outdated design mismatching with modern
toolkits), and we have to take care of these things explicitly.

Simply do this by manually querying and using the parent window event
flags.

This restores some MPlayer behavior (it doesn't add back exactly the
same code, but it's very similar).

This probably has some potential to interfere with libmpv embedding, so
bump the client API minor.

CC: @mpv-player/stable (if applied, client-api-changes.rst has to be
    adjusted to include the 0.5.2 release)

3 files changed, 12 insertions, 6 deletions

diff --git a/DOCS/client-api-changes.rst b/DOCS/client-api-changes.rst
index bef6759877..b689921e48 100644
--- a/DOCS/client-api-changes.rst
+++ b/DOCS/client-api-changes.rst
@@ -25,6 +25,7 @@ API changes
 
 ::
 
+ 1.4    - subtle change in X11 and "--wid" behavior
  --- mpv 0.5.0 is released ---
  1.3    - add MPV_MAKE_VERSION()
  1.2    - remove "stream-time-pos" property (no replacement)
diff --git a/libmpv/client.h b/libmpv/client.h
index b9ec85576c..1b41a43361 100644
--- a/libmpv/client.h
+++ b/libmpv/client.h
@@ -162,7 +162,7 @@ extern "C" {
  * relational operators (<, >, <=, >=).
  */
 #define MPV_MAKE_VERSION(major, minor) (((major) << 16) | (minor) | 0UL)
-#define MPV_CLIENT_API_VERSION MPV_MAKE_VERSION(1, 3)
+#define MPV_CLIENT_API_VERSION MPV_MAKE_VERSION(1, 4)
 
 /**
  * Return the MPV_CLIENT_API_VERSION the mpv source has been compiled with.
diff --git a/video/out/x11_common.c b/video/out/x11_common.c
index e9389c5f38..9da95ab200 100644
--- a/video/out/x11_common.c
+++ b/video/out/x11_common.c
@@ -1242,11 +1242,16 @@ static void vo_x11_map_window(struct vo *vo, struct mp_rect rc)
     }
 
     // map window
-    vo_x11_selectinput_witherr(vo, x11->display, x11->window,
-                               StructureNotifyMask | ExposureMask |
-                               KeyPressMask | KeyReleaseMask |
-                               ButtonPressMask | ButtonReleaseMask |
-                               PointerMotionMask | LeaveWindowMask);
+    int events = StructureNotifyMask | ExposureMask;
+    if (vo->opts->WinID > 0) {
+        XWindowAttributes attribs;
+        if (XGetWindowAttributes(x11->display, vo->opts->WinID, &attribs))
+            events |= attribs.your_event_mask;
+    } else {
+        events |= KeyPressMask | KeyReleaseMask | ButtonPressMask |
+                  ButtonReleaseMask | PointerMotionMask | LeaveWindowMask;
+    }
+    vo_x11_selectinput_witherr(vo, x11->display, x11->window, events);
     XMapWindow(x11->display, x11->window);
 }