Subwindow detach: Fix minor pos & size issues

src/gui/SubWindow.cpp

@@ -26,9 +26,11 @@
 
 #include "SubWindow.h"
 
-#include <QMdiArea>
-#include <QMoveEvent>
-#include <QScrollBar>
+#include <QtCore/QMetaMethod>
+#include <QtGui/QMoveEvent>
+#include <QtGui/QWindow>
+#include <QtWidgets/QMdiArea>
+#include <QtWidgets/QScrollBar>
 
 #include "embed.h"
 
@@ -233,20 +235,28 @@ void SubWindow::detach()
 	auto pos = mapToGlobal(widget()->pos());
 	widget()->setWindowFlags(Qt::Window);
 	widget()->show();
-	widget()->move(pos);
 	hide();
+
+	widget()->windowHandle()->setPosition(pos);
 }
 
 void SubWindow::attach()
 {
 	if (! widget()->windowFlags().testFlag(Qt::Window)) {
 		return;
 	}
-	auto pos = widget()->pos();
+	auto frame = widget()->windowHandle()->frameGeometry();
+
 	widget()->setWindowFlags(Qt::Widget);
 	widget()->show();
 	show();
-	move(mdiArea()->mapFromGlobal(pos));
+
+	// Delay moving & resizing using event queue. Ensures that this widget is
+	// visible first, so that resizing works.
+	QObject o;connect(&o, &QObject::destroyed, this, [this, frame]() {
+		move(mdiArea()->mapFromGlobal(frame.topLeft()));
+		resize(frame.size());
+	}, Qt::QueuedConnection);
 }