When using the Balsamiq tool for sketching an answer, we often need to look at the question to see more details and to get the mockup right. Since Balsamiq opens in the same tab as the question, it forces us to either navigate back and forth between UX.SE and Balsamiq, or to open UX.SE in a new tab and locate the question again.
I think it would be much more convenient if Balsamiq opened in a new tab, which would close once the tool is closed. Not sure if that last bit is possible.