Proposed patch provides support for selection of mouse button used in PanAction in Visual Library API. The proposed implementation provides default MouseEvent.BUTTON2, i.e. mouse wheel, which is compatible with current feature.

Usage example:
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scene.getActions().addAction(ActionFactory.createPanAction());
scene.getInputBindings().setPanActionButton(MouseEvent.BUTTON1);

The above peace of code creates an action to pan scene inside a scroll pane with left mouse button pressed instead of the default, i.e. mouse wheel pressed.

Use case:
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Many GIS and similar applications (at least for Windows) use left mouse button for pan action. Proposed change provides simple means for creation of applications with similar user experience without a need of rewriting the pan action.