Its not Evernote specific, that was just a screen shot I posted on a Mobileread forum months ago that I was able to grab.
But some progress
I was able to get shots of context menu's in File Explorer, Evernote, xplorer2, 1by1, Irfan View, without using a delay.
I cannot get screen shots of context menus in Outlook 2007 and Word 2007 with or without a delay. But that doesn't bother me as I've never had any need to do it.
I've discovered that the problem is limited to two applications - calibre book manager, and the sigil epub editor. The common link between those two applications is that they both use the Qt5 framework. I think a recent change in SC has triggered something that makes Qt dismiss the context menu, I say this because the version of Sigil I'm using was built back in April. Qt5 is a fiddelsome thing that often throws up weird incompatibilities .
I'll try the beta version - mean time is there somewhere I can get older versions of SC for testing with calibre and sigil.