dim the game behind dialogs and escape menu

src/ui/ModalDimOverlay.cpp

@@ -0,0 +1,46 @@
+#include "ModalDimOverlay.h"
+
+#include <QPainter>
+
+ModalDimOverlay::ModalDimOverlay(const QColor& dimColor, QWidget* parent)
+    : QWidget(parent)
+    , m_dimColor(dimColor)
+{
+    setAttribute(Qt::WA_TransparentForMouseEvents, true);
+    hide();
+}
+
+void ModalDimOverlay::pushModal()
+{
+    if (m_modalDepth++ == 0)
+    {
+        raise();
+        show();
+        // Force an immediate synchronous paint so the scrim is visible before the
+        // caller enters a blocking dialog exec() (no undimmed frame flashes through).
+        repaint();
+    }
+}
+
+void ModalDimOverlay::popModal()
+{
+    if (m_modalDepth > 0 && --m_modalDepth == 0)
+    {
+        hide();
+    }
+}
+
+void ModalDimOverlay::setDimColor(const QColor& dimColor)
+{
+    m_dimColor = dimColor;
+    if (isVisible())
+    {
+        update();
+    }
+}
+
+void ModalDimOverlay::paintEvent(QPaintEvent* /*event*/)
+{
+    QPainter painter(this);
+    painter.fillRect(rect(), m_dimColor);
+}