In the polyg command and if one or more polygons is selected, a vertex editing mode is active on the selected polygons. Each vertex of the selected object is marked with a small highlighting box. Clicking on a vertex will delete the vertex. Clicking on the edge of a selected polygon away from an existing vertex will create a new vertex, which can subsequently be moved. To move vertices, one or more must be selected. This is accomplished by holding the Shift key, and clicking over a vertex, or dragging over one or more vertices. This operation can be repeated. Selecting a vertex a second time will deselect it. When a vertex is selected, all vertex marks disappear, except for the selected vertices, which are marked with a slightly larger highlighting box. When there are selected vertices, all selected vertices can be moved by clicking twice or dragging. The selected vertices will be translated according to the button-down location and the button up location, or the next button-down location if the pointer didn't move. While the translation is in progress, the new borders are ghost-drawn.
While in the polyg command, with no object in the process of being created, it is possible to change the selected state of polygon objects, thus displaying the vertices and allowing vertex editing. Pressing the Enter key will cause the next button 1 operation to select (or deselect) polygon objects. This can be repeated arbitrarily. When one of these objects is selected, the vertices are marked, and vertex editing is possible.
If the vertex editor is active, i.e., a selected polygon is shown with the vertices marked, clicking with the Ctrl button pressed will start a new polygon, overriding the vertex editor. This can be used to start a new polygon at a marked vertex location, for example. Without Ctrl pressed, the vertex editor would have precedence and would delete the marked vertex instead of starting a new polygon.
While moving vertices, holding the Shift key will enable or disable constraining the translation angle to multiples of 45 degrees. If the Constrain 45 button in the Attributes Menu is set, Shift will disable the constraint, otherwise the constraint will be enabled. The Shift key must be up when the button-down occurs which starts the translation operation, and can be pressed before the operation is completed to alter the constraint. These operations are similar to operations in the Stretch command.