Introduce View::handle() and View::equals()

So we can compare two windows without calling asQWidget().

src/View.cpp

@@ -183,3 +183,13 @@ Controllers::FloatingWindow *View::asFloatingWindowController() const
 
     return nullptr;
 }
+
+bool View::equals(const View *other) const
+{
+    return other && handle() == other->handle();
+}
+
+bool View::equals(const std::unique_ptr<ViewWrapper> &other) const
+{
+    return other && handle() == other->handle();
+}

src/View.h

@@ -38,6 +38,8 @@ namespace Controllers {
 class FloatingWindow;
 }
 
+using HANDLE = const void *;
+
 class DOCKS_EXPORT View
 {
 public:
@@ -71,6 +73,16 @@ public:
     /// as the implementation of free() is free to delay it (with deleteLater() for example)
     bool inDtor() const;
 
+    /// @brief Returns whether this view represents the same GUI element as the other
+    bool equals(const View *other) const;
+    bool equals(const std::unique_ptr<ViewWrapper> &) const;
+
+    /// @brief Returns a handle for the GUI element
+    /// This value only makes sense to the frontend. For example, for QtQuick it might be a
+    /// QtQuickItem, while for QtWidgets it's a QWidget *. Can be whatever the frontend developer wants,
+    /// as long as it uniquely identifies the GUI element. KDDW backend only uses it for comparison purposes
+    virtual HANDLE handle() const = 0;
+
     /// @brief Called by the layouting engine
     /// Override it in case your widget needs to know where it is in the layout. Usually only needed by Frame.s
     virtual void setLayoutItem(Layouting::Item *) {};

src/controllers/Frame.cpp

@@ -566,7 +566,7 @@ FloatingWindow *Frame::floatingWindow() const
         if (auto fw = p->asFloatingWindowController())
             return fw;
 
-        if (p->asQWidget() == view()->window()->asQWidget()) {
+        if (p->equals(view()->window())) {
             // We stop at the window. (top-levels can have parent, but we're not interested)
             return nullptr;
         }

src/views_qtwidgets/ViewWrapper_qtwidgets.cpp

@@ -213,3 +213,8 @@ std::unique_ptr<ViewWrapper> ViewWrapper_qtwidgets::parentView() const
 {
     return std::unique_ptr<ViewWrapper>(new ViewWrapper_qtwidgets(m_widget->parentWidget()));
 }
+
+HANDLE ViewWrapper_qtwidgets::handle() const
+{
+    return reinterpret_cast<HANDLE>(m_widget);
+}

src/views_qtwidgets/ViewWrapper_qtwidgets.h

@@ -43,6 +43,7 @@ public:
     bool is(Type) const override;
     std::unique_ptr<ViewWrapper> window() const override;
     std::unique_ptr<ViewWrapper> parentView() const override;
+    HANDLE handle() const override;
 
 private:
     QWidget *const m_widget;

src/views_qtwidgets/View_qtwidgets.h

@@ -311,6 +311,11 @@ public:
         return QWidget::windowHandle();
     }
 
+    HANDLE handle() const override
+    {
+        return reinterpret_cast<HANDLE>(this);
+    }
+
     std::unique_ptr<ViewWrapper> window() const override
     {
         ViewWrapper *wrapper = new ViewWrapper_qtwidgets(QWidget::window());