FIX: [STUDIO-2186] hide PopupWindow on alt-tab

Change-Id: Ie1bffdd9ace2c6e05979743da9f75ca2c1e87cf4
(cherry picked from commit 7ddaf5260df19c76fca82e525caca26e55732fa9)

src/slic3r/GUI/Widgets/PopupWindow.cpp

@@ -0,0 +1,37 @@
+#include "PopupWindow.hpp"
+
+static wxWindow *GetTopParent(wxWindow *pWindow)
+{
+    wxWindow *pWin = pWindow;
+    while (pWin->GetParent()) {
+        pWin = pWin->GetParent();
+        if (auto top = dynamic_cast<wxNonOwnedWindow*>(pWin))
+            return top;
+    }
+    return pWin;
+}
+
+bool PopupWindow::Create(wxWindow *parent, int style)
+{
+    if (!wxPopupTransientWindow::Create(parent, style))
+        return false;
+#ifdef __WXGTK__
+    GetTopParent(parent)->Bind(wxEVT_ACTIVATE, &PopupWindow::topWindowActiavate, this);
+#endif
+    return true;
+}
+
+PopupWindow::~PopupWindow()
+{
+#ifdef __WXGTK__
+    GetTopParent(this)->Unbind(wxEVT_ACTIVATE, &PopupWindow::topWindowActiavate, this);
+#endif
+}
+
+#ifdef __WXGTK__
+void PopupWindow::topWindowActiavate(wxActivateEvent &event)
+{
+    event.Skip();
+    if (!event.GetActive() && IsShown()) DismissAndNotify();
+}
+#endif