Qt: Initial shader editor support

include/panda_qt/shader_editor.hpp

@@ -0,0 +1,28 @@
+#pragma once
+
+#include <QApplication>
+#include <QDialog>
+#include <QWidget>
+#include <string>
+
+#include "zep.h"
+#include "zep/mode_repl.h"
+#include "zep/regress.h"
+
+class ShaderEditorWindow : public QDialog {
+	Q_OBJECT
+
+  private:
+	Zep::ZepWidget_Qt zepWidget;
+	Zep::IZepReplProvider replProvider;
+	static constexpr float fontSize = 14.0f;
+
+	// Whether this backend supports shader editor
+	bool shaderEditorSupported = true;
+
+  public:
+	ShaderEditorWindow(QWidget* parent, const std::string& filename, const std::string& initialText);
+	void setText(const std::string& text) { zepWidget.GetEditor().GetMRUBuffer()->SetText(text); }
+
+	void setEnable(bool enable);
+};