wayland: Fix focus follows mouse policy

We want to update the input focus only if the pointer is moved. Due to
that, AbstractClient::enterEvent() checks the last seen pointer position
to decide whether the window needs to be focused.

The issue is that when the pointer moves from a decoration to a surface,
the cached pointer position will be updated to the current pointer
position, and thus the check in AbstractClient::enterEvent() will fail.

We need to update the cached pointer position only if there is a focused
decoration.

src/input.cpp

@@ -2846,6 +2846,7 @@ void InputDeviceHandler::update()
     setAt(toplevel);
 
     if (focusUpdatesBlocked()) {
+        workspace()->updateFocusMousePosition(position().toPoint());
         return;
     }
 
@@ -2860,21 +2861,20 @@ void InputDeviceHandler::update()
             // went onto or off from decoration, update focus
             updateFocus();
         }
-        return;
-    }
-    updateInternalWindow(nullptr);
+    } else {
+        updateInternalWindow(nullptr);
 
-    if (m_focus.focus != m_at.at) {
-        // focus change
-        updateDecoration();
-        updateFocus();
-        return;
-    }
-    // check if switched to/from decoration while staying on the same Toplevel
-    if (updateDecoration()) {
-        // went onto or off from decoration, update focus
-        updateFocus();
+        if (m_focus.focus != m_at.at) {
+            // focus change
+            updateDecoration();
+            updateFocus();
+        } else if (updateDecoration()) {
+            // went onto or off from decoration, update focus
+            updateFocus();
+        }
     }
+
+    workspace()->updateFocusMousePosition(position().toPoint());
 }
 
 Toplevel *InputDeviceHandler::at() const

src/pointer_input.cpp

@@ -473,7 +473,6 @@ void PointerInputRedirection::cleanupDecoration(Decoration::DecoratedClientImpl
 {
     disconnect(m_decorationGeometryConnection);
     m_decorationGeometryConnection = QMetaObject::Connection();
-    workspace()->updateFocusMousePosition(position().toPoint());
 
     if (old) {
         // send leave event to old decoration
@@ -524,7 +523,6 @@ void PointerInputRedirection::focusUpdate(Toplevel *focusOld, Toplevel *focusNow
 
     if (AbstractClient *ac = qobject_cast<AbstractClient*>(focusNow)) {
         ac->enterEvent(m_pos.toPoint());
-        workspace()->updateFocusMousePosition(m_pos.toPoint());
     }
 
     if (internalWindow()) {