Custom MSBuild Task: how to flush logging in VS2012 output window while task is still running?

Question

I have a custom MSBuild task that takes some time to complete. It outputs progress using either Log.LogMessage() or BuildEngine.LogMessageEvent() (

Answer 1

Known bug in VS2012.

We ended up making a VSPackage extension for VS2012/2013 (to directly output in pane log).

It is fixed in VS2015.