Hi all, by chance, I stumbled upon this thread - http://discourse.techart.online/t/problems-with-mayamixin-and-pyside-events/8788/8 and following the Maya Google link.
It seems that, when my tool is docked, anywhere within Maya, and closing the tool (when it is docked), the dockCloseEventTriggered is actually being called! But no when it is Not docked.
This has definitely stumps me. Even so, the solution does not seems to work for me when it is ‘un-docked’ though.