nodeparamview: separated the NodeParamView body into a separate widget for nesting

Will allow display of NodeInputArrays.

app/widget/collapsebutton/collapsebutton.h

@@ -0,0 +1,43 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2019 Olive Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef COLLAPSEBUTTON_H
+#define COLLAPSEBUTTON_H
+
+#include <QPushButton>
+
+#include "common/define.h"
+
+OLIVE_NAMESPACE_ENTER
+
+class CollapseButton : public QPushButton
+{
+  Q_OBJECT
+public:
+  CollapseButton(QWidget* parent = nullptr);
+
+private slots:
+  void UpdateIcon(bool e);
+
+};
+
+OLIVE_NAMESPACE_EXIT
+
+#endif // COLLAPSEBUTTON_H