You can select any polygon by clicking on it in the editor window or the tree. You will recognize the selected polygon, as its vertices are shown in the form of black squares.
Whenever a polygon is selected, you can access the following functions via a popup window if you right klick on that polygon:
"Add vertex" adds a new vertex to the polygon at the click position.
"Remove selected object" removes the polygon. Alternatively, you may use the key "backspace" in Windows or "Del" to remove the object.
“Change type of polygon” enables you to alter the type of a previously created polygon. Other properties, like balloon texts or names, are saved as long as both object types contain this category.
Click on a vertex in order to select it.
Click on a free space in order to remove a previous selection.
In the form view, you can see the properties of the selected polygon and modify it. The corresponding elements are highlighted within the hierarchy and the XML view
Whenever a vertex is selected, you can access the following functions:
A right click and "Remove vertex" removes this vertex. Alternatively, you may use the key "backspace" in Windows or "Del" to remove the vertex.
Left click and drag a selected, blue vertex in order to change its position and thereby change the polygon to which this vertex belongs.