Flow inspector: Panels don't move when you scroll the page

[narenranjit]

Listen for scroll and update

[mmrj]

tested on chrome, variations of (local.forio.com + python model) and (epicenter.com/app + fml model).

reopening because:

• verified that when you have a long page (scrollable ui), you can scroll it ... the entire page stays grey (even below the fold) and the legend and context windows stay where they are relative to the frame (that is, if the legend window is near the top of the page and you scroll, the legend window stays near the top of the visible frame even though the portion of the page you're looking at has changed).
• however, if, after scrolling, you click on either the legend window or the context window to drag them again, they disappear completely and i can't bring them back.