ViewGuard: Add a copy-ctor

src/ViewGuard.cpp

@@ -19,6 +19,11 @@ ViewGuard::ViewGuard(View *view)
     setView(view);
 }
 
+ViewGuard::ViewGuard(const ViewGuard &other)
+{
+    setView(other.view());
+}
+
 ViewGuard::~ViewGuard()
 {
     clear();

src/ViewGuard.h

@@ -25,6 +25,7 @@ class DOCKS_EXPORT ViewGuard
 {
 public:
     ViewGuard(View *v);
+    ViewGuard(const ViewGuard &);
     ~ViewGuard();
 
     operator bool() const;