In the 2021 Developers Survey, Visual Studio Code continues to be ranked #1, with 70% of the 82,000 respondents using it. post 
In 2011, Microsoft made a high-profile hire. Former IBMer and technical lead on Eclipse Java development tools, Erich Gamma, joined the company to work on an unspecified project. Microsoft officials said he'd open a lab in Zurich, Switzerland. And that's about all they revealed. post
Gamma hit the "open-source button" for VS Code's GitHub repository on stage at a Microsoft conference in 2015 as part of his demonstration of the editor's broad extension support. To make the point clear, he demonstrated VS Code with the then Microsoft-maintained Go extension. post
The idea behind the Language Server Protocol (LSP) is to standardize the protocol for how such servers and development tools communicate. This way, a single Language Server can be re-used in multiple development tools, which in turn can support multiple languages with minimal effort. site
Vague memory has Erich spending some time at Taligent where committed himself to ui modules. wikipedia