Resolve some TODOs

* 12to11.c (PickVisual): Remove redundant TODOs.
* dmabuf.c (CreateHeader): Handle flags like wlroots.
* dnd.c (HandleXdndPositionEvent):
* subsurface.c:
* xdg_surface.c (CurrentRootPosition, XLGetXdgSurface): Remove
outdated TODOs.

12to11.c

@@ -46,7 +46,6 @@ PickVisual (int *depth)
 
   if (n_visuals)
     {
-      /* TODO: verify visual format.  */
       selection = visuals[0].visual;
       *depth = visuals[0].depth;
       XFree (visuals);

dmabuf.c

@@ -684,7 +684,7 @@ XLHandleOneXEventForDmabuf (XEvent *event)
 #define CreateHeader									\
   BufferParams *params;									\
   int num_buffers, i, depth, bpp;							\
-  uint32_t mod_high, mod_low;								\
+  uint32_t mod_high, mod_low, all_flags;						\
   int32_t *allfds;									\
 											\
   params = wl_resource_get_user_data (resource);					\
@@ -752,7 +752,25 @@ XLHandleOneXEventForDmabuf (XEvent *event)
       goto inert_error;									\
     }											\
 											\
-  /* TODO: handle flags.  */								\
+  all_flags = (ZWP_LINUX_BUFFER_PARAMS_V1_FLAGS_Y_INVERT				\
+	       | ZWP_LINUX_BUFFER_PARAMS_V1_FLAGS_INTERLACED				\
+	       | ZWP_LINUX_BUFFER_PARAMS_V1_FLAGS_BOTTOM_FIRST);			\
+											\
+  if (flags & ~all_flags)								\
+    {											\
+      wl_resource_post_error (resource,							\
+			      ZWP_LINUX_BUFFER_PARAMS_V1_ERROR_INVALID_FORMAT, 		\
+			      "invalid dmabuf flags: %u", flags);			\
+      goto inert_error;									\
+    }											\
+											\
+  if (flags)										\
+    {											\
+      /* Flags are not supported by wlroots, so I guess we don't have			\
+	 to either.  */									\
+      zwp_linux_buffer_params_v1_send_failed (resource);				\
+      goto inert_error;									\
+    }											\
 											\
   /* Copy the file descriptors into a buffer.  At this point, we know			\
      there are no gaps in params->entries.  */						\

dnd.c

@@ -990,8 +990,6 @@ HandleXdndPositionEvent (Surface *surface, XEvent *event)
   uint32_t action;
   Bool sent_actions;
 
-  /* TODO: handle subsurfaces.  */
-
   if (event->xclient.data.l[0] != dnd_state.source_window)
     /* The message is coming from the wrong window, or drag and drop
        has not yet been set up.  */
@@ -1011,7 +1009,6 @@ HandleXdndPositionEvent (Surface *surface, XEvent *event)
 			 XLWindowFromSurface (surface),
 			 root_x, root_y, &x, &y, &child);
 
-  /* Compute the action.  TODO: handle multiple actions.  */
   action = TranslateAction (event->xclient.data.l[4]);
 
   /* Handle mouse motion.  */

subsurface.c

@@ -22,8 +22,6 @@ along with 12to11.  If not, see <https://www.gnu.org/licenses/>.  */
 
 #include "compositor.h"
 
-/* TODO: handle unmapping nested subsurfaces.  */
-
 enum
   {
     PendingPosition	 = 1,

xdg_surface.c

@@ -1049,8 +1049,6 @@ CurrentRootPosition (XdgRole *role, int *root_x, int *root_y)
       return;
     }
 
-  /* TODO: handle root position changing in quick succession and avoid
-     call to XTranslateCoordinates.  */
   XTranslateCoordinates (compositor.display, role->window,
 			 DefaultRootWindow (compositor.display),
 			 0, 0, root_x, root_y, &child_return);
@@ -1285,9 +1283,6 @@ XLGetXdgSurface (struct wl_client *client, struct wl_resource *resource,
       return;
     }
 
-  /* TODO: post more errors if the surface is not in a valid
-     state.  */
-
   role = XLSafeMalloc (sizeof *role);
 
   if (!role)