No API for Stencil Windows?

I often work with multiple stencil sets simultaneously, and so open them in separate windows. Unfortunately, I’m unable to programmatically manipulate such windows using AppleScript. For example, the list resulting from…

tell application "OmniGraffle"
	windows
end tell

…is the same whether stencil windows are open or closed. There appears to simply be no API for them. They’re manipulable via GUI scripting, but that’s hellish.

Am I missing something?

For clarity, I’m referring to windows produced thusly:

2024-09-01_17-33-17