feat: add Preferences dialog for managing theme, rendering, and unit settings

app/gcompose/src/PreferencesDialog.h

@@ -0,0 +1,31 @@
+#ifndef GCOMPOSE_PREFERENCESDIALOG_H
+#define GCOMPOSE_PREFERENCESDIALOG_H
+
+#include <QDialog>
+#include <QCheckBox>
+#include <QComboBox>
+#include <map>
+#include <string>
+#include "Settings.h"
+
+namespace uLib {
+namespace Qt {
+
+class PreferencesDialog : public QDialog {
+    Q_OBJECT
+public:
+    explicit PreferencesDialog(QWidget* parent = nullptr);
+
+private slots:
+    void onAccept();
+
+private:
+    QCheckBox* m_throttledRendering;
+    QComboBox* m_themeCombo;
+    std::map<Settings::Dimension, QComboBox*> m_unitCombos;
+};
+
+} // namespace Qt
+} // namespace uLib
+
+#endif