groups: fix swallowing (#8223)

* fix swallowing for groups

* remove unnecessary check

* clang-format

* clarify comment

* make variables consistent

* make aditional variables consistent

src/desktop/Window.hpp

@@ -357,6 +357,7 @@ class CWindow {
 
     // swallowing
     PHLWINDOWREF m_pSwallowed;
+    bool         m_bGroupSwallowed = false;
 
     // focus stuff
     bool m_bStayFocused = false;