Fix overlay disappearing when we were resizing

We allow the user to click 4px outside of the overlay for better
resizing. But we also had code that would hide the overlay if we
clicked elsewhere. So these two requirements were in conflict.

So, before hidding, check if the frame accepted the press.

Also for issue #118

src/private/DockRegistry.cpp

@@ -627,12 +627,15 @@ bool DockRegistry::eventFilter(QObject *watched, QEvent *event)
         if (!(Config::self().flags() & Config::Flag_AutoHideSupport))
             return false;
 
+        if (qobject_cast<Frame*>(watched)) {
+            // break recursion
+            return false;
+        }
+
         auto p = watched;
         while (p) {
-            if (auto dw = qobject_cast<DockWidgetBase*>(p)) {
-                onDockWidgetPressed(dw);
-                return false;
-            }
+            if (auto dw = qobject_cast<DockWidgetBase*>(p))
+                return onDockWidgetPressed(dw, static_cast<QMouseEvent*>(event));
 
             p = p->parent();
         }
@@ -641,17 +644,29 @@ bool DockRegistry::eventFilter(QObject *watched, QEvent *event)
     return false;
 }
 
-void DockRegistry::onDockWidgetPressed(DockWidgetBase *dw)
+bool DockRegistry::onDockWidgetPressed(DockWidgetBase *dw, QMouseEvent *ev)
 {
     // Here we implement "auto-hide". If there's a overlayed dock widget, we hide it if some other
     // dock widget is clicked.
 
     MainWindowBase *mainWindow = dw->mainWindow();
     if (!mainWindow) // Only docked widgets are interesting
-        return;
+        return false;
 
-    DockWidgetBase *overlayedDockWidget = mainWindow->overlayedDockWidget();
-    if (overlayedDockWidget && dw != overlayedDockWidget) {
-        mainWindow->clearSideBarOverlay();
+    if (DockWidgetBase *overlayedDockWidget = mainWindow->overlayedDockWidget()) {
+        ev->ignore();
+        qApp->sendEvent(overlayedDockWidget->frame(), ev);
+
+        if (ev->isAccepted()) {
+            // The Frame accepted it. It means the user is resizing it. We allow for 4px outside for better resize.
+            return true; // don't propagate the event further
+        }
+        if (dw != overlayedDockWidget) {
+            // User clicked outside if the overlay, then we close the overlay.
+            mainWindow->clearSideBarOverlay();
+            return false;
+        }
     }
+
+    return false;
 }

src/private/DockRegistry_p.h

@@ -209,7 +209,7 @@ protected:
 private:
     friend class FocusScope;
     explicit DockRegistry(QObject *parent = nullptr);
-    void onDockWidgetPressed(DockWidgetBase *dw);
+    bool onDockWidgetPressed(DockWidgetBase *dw, QMouseEvent *);
     void onFocusObjectChanged(QObject *obj);
     void maybeDelete();
     void setFocusedDockWidget(DockWidgetBase *);