Can anyone confirm this for me? (I'm testing in Inventor 2013)
Inventor appears to measure the width of a panel by measuring it's distance from the edge of the screen. This only works if that panel is docked directly to the edge of the screen. In my case, there is a panel between the one I'm inserting and the edge of the screen.
To test, insert a docked panel. Retrieve its width when it is docked to the very edge of the screen, and also when it is docked to another panel. The actual width of the panel remains the same, but Inventor will report the width to be much larger.
I can reproduce this issue. It looks if the dock pane window docks with any other docked pane (no matter the pane is docked left or right), the custom dock pane returns the width from the left edge. I logged this issue with engineer team.
A kindly reminding: if you find issue, please try to isolate and share a small. buildable sample project. This will help the peers in the board to take a look and diagnose. I just happened to have a small project, so gave a test.