*: handle FocusIn events

Some programs call XSetInputFocus(), so we should select
FocusChangeEvent and handle FocusIn events, calling vwm_win_set_focus()
when appropriate.

It's rare, but SDL2 programs in particular seem to do this and vwm gets
in a pretty annoying state when it does occur.  This change should
improve the situation.

4 files changed, 28 insertions, 3 deletions

diff --git a/src/vwm.c b/src/vwm.c
index 179b1dc..c2c3027 100644
--- a/src/vwm.c
+++ b/src/vwm.c
@@ -126,7 +126,7 @@ static vwm_t * vwm_startup(void)
 #undef color
 
 	XSelectInput(VWM_XDISPLAY(vwm), VWM_XROOT(vwm),
-		     PropertyChangeMask | SubstructureNotifyMask | SubstructureRedirectMask | PointerMotionMask | ButtonPressMask | ButtonReleaseMask);
+		     FocusChangeMask | PropertyChangeMask | SubstructureNotifyMask | SubstructureRedirectMask | PointerMotionMask | ButtonPressMask | ButtonReleaseMask);
 	XGrabKey(VWM_XDISPLAY(vwm), AnyKey, WM_GRAB_MODIFIER, VWM_XROOT(vwm), False, GrabModeAsync, GrabModeAsync);
 
 	XFlush(VWM_XDISPLAY(vwm));
@@ -259,6 +259,15 @@ void vwm_process_event(vwm_t *vwm)
 			vwm_xevent_handle_property_notify(vwm, &event.xproperty);
 			break;
 
+		case FocusIn:
+			VWM_TRACE("focusin");
+			vwm_xevent_handle_focusin(vwm, &event.xfocus);
+			break;
+
+		case FocusOut:
+			VWM_TRACE("focusout");
+			break;
+
 		case MappingNotify:
 			VWM_TRACE("mapping notify");
 			vwm_xevent_handle_mapping_notify(vwm, &event.xmapping);
diff --git a/src/xevent.c b/src/xevent.c
index e1b38e3..a14f37e 100644
--- a/src/xevent.c
+++ b/src/xevent.c
@@ -227,6 +227,19 @@ void vwm_xevent_handle_property_notify(vwm_t *vwm, XPropertyEvent *ev)
 }
 
 
+void vwm_xevent_handle_focusin(vwm_t *vwm, XFocusInEvent *ev)
+{
+	vwm_window_t	*vwin;
+
+	if (ev->mode != NotifyNormal)
+		return;
+
+	if ((vwin = vwm_win_lookup(vwm, ev->window)) &&
+	    (vwin != vwm_win_get_focused(vwm)))
+		vwm_win_set_focused(vwm, vwin);
+}
+
+
 void vwm_xevent_handle_mapping_notify(vwm_t *vwm, XMappingEvent *ev)
 {
 	XRefreshKeyboardMapping(ev);
diff --git a/src/xevent.h b/src/xevent.h
index dc710fd..da9a828 100644
--- a/src/xevent.h
+++ b/src/xevent.h
@@ -15,4 +15,5 @@ void vwm_xevent_handle_unmap_notify(vwm_t *vwm, XUnmapEvent *ev);
 void vwm_xevent_handle_map_notify(vwm_t *vwm, XMapEvent *ev);
 void vwm_xevent_handle_map_request(vwm_t *vwm, XMapRequestEvent *ev);
 void vwm_xevent_handle_property_notify(vwm_t *vwm, XPropertyEvent *ev);
+void vwm_xevent_handle_focusin(vwm_t *vwm, XFocusInEvent *ev);
 void vwm_xevent_handle_mapping_notify(vwm_t *vwm, XMappingEvent *ev);
diff --git a/src/xwindow.c b/src/xwindow.c
index 1aa4f71..6fc9691 100644
--- a/src/xwindow.c
+++ b/src/xwindow.c
@@ -159,8 +159,10 @@ vwm_xwindow_t * vwm_xwin_create(vwm_t *vwm, Window win, vwm_grab_mode_t grabbed)
 	XFetchName(VWM_XDISPLAY(vwm), win, &xwin->name);
 
 	/* This is so we get the PropertyNotify event and can get the pid when it's set post-create,
-	 * with my _NET_WM_PID patch the property is immediately available */
-	XSelectInput(VWM_XDISPLAY(vwm), win, PropertyChangeMask);
+	 * with my _NET_WM_PID patch the property is immediately available.
+	 * FocusChangeMask is needed to notice when clients call XSetInputFocus().
+	 */
+	XSelectInput(VWM_XDISPLAY(vwm), win, PropertyChangeMask | FocusChangeMask);
 
 	/* we must track the mapped-by-client state of the window independent of managed vs. unmanaged because
 	 * in the case of override_redirect windows they may be unmapped (invisible) or mapped (visible) like menus without being managed.