I'd like to share a user control I wrote for a client. He wanted to select a shape element and plot only what was inside the shape. The user control makes a mask around the shape. Then the user can adjust the view as he likes and then plot it.
For those of you who have written user controls for GTViewer, this will be old hat. For those who have not yet attempted one, this could be an easy start. It illustrates how to capture a feature that the user selects and do something based on that feature.
As with all user controls, make an entry in the .gtm file in the [External Applications] section, as documented in gtvconfig.doc in the 5.0 release. Then register the .ocx file, and GTViewer will automatically place it on the Query menu. When you open the .gtm file.
Sample code can be downloaded from http://www.gti-us.com/Blog/PlotShape.zip