Only send WM_TAKE_FOCUS when the client supports it in the protocols atom

Fixes opening xterm, for example

include/data.h

@@ -246,6 +246,9 @@ struct Window {
     /** Whether the application used _NET_WM_NAME */
     bool uses_net_wm_name;
 
+    /** Whether the application needs to receive WM_TAKE_FOCUS */
+    bool needs_take_focus;
+
     /** Whether the window says it is a dock window */
     enum { W_NODOCK = 0, W_DOCK_TOP = 1, W_DOCK_BOTTOM = 2 } dock;
 

include/x.h

@@ -39,6 +39,12 @@ void x_reinit(Con *con);
  */
 void x_con_kill(Con *con);
 
+/**
+ * Returns true if the client supports the given protocol atom (like WM_DELETE_WINDOW)
+ *
+ */
+bool window_supports_protocol(xcb_window_t window, xcb_atom_t atom);
+
 /**
  * Kills the given X11 window using WM_DELETE_WINDOW (if supported).
  *

include/xcb.h

@@ -116,6 +116,12 @@ void fake_configure_notify(xcb_connection_t *conn, Rect r, xcb_window_t window);
  */
 void fake_absolute_configure_notify(Con *con);
 
+/**
+ * Sends the WM_TAKE_FOCUS ClientMessage to the given window
+ *
+ */
+void send_take_focus(xcb_window_t window);
+
 /**
  * Finds out which modifier mask is the one for numlock, as the user may
  * change this.