Fix MainWindow being out of focus when the fullscreen overlay is closed

That was probably a Linux specific issue or my mouse is buggy.

include/ImageOverlayDialog.h

@@ -32,6 +32,12 @@ protected:
 	void mousePressEvent(QMouseEvent *event) override;
 	void paintEvent(QPaintEvent *event) override;
 
+signals:
+	void closing();
+
+private slots:
+	void closeDialog();
+
 private:
 	void scaleImage(int width, int height);
 

src/ImageOverlayDialog.cc

@@ -17,6 +17,7 @@
 
 #include <QDebug>
 #include <QPainter>
+#include <QTimer>
 
 #include "ImageOverlayDialog.h"
 
@@ -36,6 +37,13 @@ ImageOverlayDialog::ImageOverlayDialog(QPixmap image, QWidget *parent)
 	setWindowState(Qt::WindowFullScreen);
 
 	raise();
+
+	connect(this, SIGNAL(closing()), this, SLOT(closeDialog()));
+}
+
+void ImageOverlayDialog::closeDialog()
+{
+	QTimer::singleShot(100, this, &ImageOverlayDialog::reject);
 }
 
 // TODO: Move this into Utils
@@ -110,9 +118,8 @@ void ImageOverlayDialog::mousePressEvent(QMouseEvent *event)
 	if (event->button() != Qt::LeftButton)
 		return;
 
-	// FIXME: The main window needs double click to regain focus.
 	if (close_button_.contains(event->pos()))
-		close();
+		emit closing();
 	else if (!content_.contains(event->pos()))
-		close();
+		emit closing();
 }