fix name in gcompose

app/gcompose/src/MainPanel.h

@@ -4,7 +4,7 @@
 #include <QWidget>
 
 class QSplitter;
-class QViewportPane;
+class ViewportPane;
 
 class MainPanel : public QWidget {
     Q_OBJECT
@@ -12,11 +12,11 @@ public:
     explicit MainPanel(QWidget* parent = nullptr);
     virtual ~MainPanel();
 
-    QViewportPane* getFirstPane() const { return m_firstPane; }
+    ViewportPane* getFirstPane() const { return m_firstPane; }
 
 private:
     QSplitter* m_rootSplitter;
-    QViewportPane* m_firstPane;
+    ViewportPane* m_firstPane;
 };
 
 #endif // MAINPANEL_H