I'm having a problem with Notepad++ v6.5. Each time I try to right-click a single selected line from the left margin (line number margin), the line is deselected and the cut/copy/paste/etc menu items are not available on the context menu. This problem also occurs when right-clicking on the first line of a group of selected lines. It does not occur when right-clicking on any line other than the first line of group of selected lines. It also doesn't occur when using Notepad++ v6.4.5 and earlier.
A user responded that this is probably a Scintilla bug that propagated to Notepad++ at the v6.5 major upgrade. He asked that I try Scintilla to see if it has the same problem. I installed Scintilla v3.3.9 and was able reproduce the same problem when right-clicking on the left margin.