Microsoft has a checkered history when it comes to the value and embrace of the open source software model. Since the vast majority of Microsoft's profits come from software any free alternatives are a threat, and for most of Microsoft's history open source software was that threat. More recently Microsoft has changed their tune when it comes to embracing open source and even open sourcing more Microsoft products and technologies.
Bits of information have been trickling out concerning the possible open source future of Windows Live Writer. This software enables users compose posts offline instead of requiring editing and posting from within web-apps. The software hasn't gotten much attention since being released in 2012 as a part of the Windows Live Essentials. However Windows Live Writer in its current form still provides bloggers with a valuable tool and the software can get more support from the open source community.
Microsoft's own Scott Hanselman has confirmed work is currently underway to open source Live Writer.
— Scott Hanselman (@shanselman) June 10, 2015
Hopefully details will be decided and shared soon and as soon as details are revealed we'll keep you up to date!