In addition to the standard panels that are active by default (like e.g. Attributes and Validation panel), the BPMN editor comes with an Overview panel. Activate this panel by clicking the icon in the top right corner. You can use this panel to navigate in your BPMN model. This is useful when the BPMN model is large and expands beyond the visible canvas.
The Overview Panel displays your model and a blue frame, representing the content shown on the diagram pane. If you wan to quickly change your working location in large models, you can move the frame to change the visible part of the model.
You can use the Overview panel to zoom in or out of the model.
Hover over the right bottom corner of the blue frame. The cursor changes and you can resize the frame.