I'm sorry, that's correct -- it's where the cursor is. However, when you assign a key to open the context menu (as if you right-clicked there), when the cursor at the top row of the pattern editor, it opens the CHANNEL Header's context menu, not the Pattern Editor's context menu (to see the difference, right-click on the space where the plugins show for each channel, then the top row of the channel's note events.)
If this isn't clear enough or if you can't reproduce it, let me know here. This week i'll try to do the same and provide an image, when i come back next weekend.