qt: fix mouse grab on opengl renderer (for windows)

src/qt/qt_hardwarerenderer.cpp

@@ -4,6 +4,7 @@
 
 extern "C" {
 #include <86box/86box.h>
+#include <86box/plat.h>
 }
 
 void HardwareRenderer::resizeGL(int w, int h)
@@ -45,3 +46,19 @@ void HardwareRenderer::resizeEvent(QResizeEvent *event) {
     onResize(width(), height());
     QOpenGLWindow::resizeEvent(event);
 }
+
+void HardwareRenderer::mouseReleaseEvent(QMouseEvent *event)
+{
+    if (this->geometry().contains(event->pos()) && event->button() == Qt::LeftButton && !mouse_capture)
+    {
+        plat_mouse_capture(1);
+        this->setCursor(Qt::BlankCursor);
+        return;
+    }
+    if (mouse_capture && event->button() == Qt::MiddleButton)
+    {
+        plat_mouse_capture(0);
+        this->setCursor(Qt::ArrowCursor);
+        return;
+    }
+}

src/qt/qt_hardwarerenderer.hpp

@@ -49,4 +49,5 @@ public slots:
 
 protected:
     void resizeEvent(QResizeEvent *event) override;
+    void mouseReleaseEvent(QMouseEvent* event) override;
 };