My mistake when committing the first change introducing the Help menu.
C:\Users\VinsWorldcom\tmp\mohzy83\NppMarkdownPanel\MarkdownPanelController.cs(181,71): error CS0117: 'Main' does not contain a definition for 'PluginFilename' [C:\Users\VinsWorldcom\tmp\mohzy83\NppMarkdownPanel\NppMarkdownPanel.csproj]
My mistake when committing the first change introducing the Help menu.
I'll submit a simple PR to fix.