Updated with native ui (imgui + qt)

Client/NativeUI-Qt/src/layout_picker.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include <QToolButton>
+#include <functional>
+
+/**
+ * A toolbar button that opens a small popup grid of layout preview buttons.
+ * Each cell draws a schematic of the grid it represents.
+ *
+ * The user clicks a cell → the popup closes → callback fires with the layout index.
+ */
+class LayoutPicker : public QToolButton {
+    Q_OBJECT
+public:
+    explicit LayoutPicker(QWidget* parent = nullptr);
+
+    /** 0-based index matching the Layout enum order:
+     *  0=1×1  1=1×2  2=1×3  3=1×4  4=2×1  5=2×2  6=3×1  7=4×1 */
+    void setCurrentLayout(int idx);
+    int  currentLayout() const { return current_; }
+
+signals:
+    void layoutSelected(int idx);
+
+private:
+    void openPopup();
+
+    int current_ = 0;
+
+    struct LayoutDef {
+        const char* label;   // e.g. "1×2"
+        int rows, cols;
+    };
+    static const LayoutDef kLayouts[8];
+};