How do you lock regular & global guidelines ?
guideline can only be moved if they where previously active. So there should be no need to look them.
First I made them only selectable by the guideline node but some people found that to difficult to find (if the node is not visible). So now you can click the whole line to select it. If you select it by accident, you should deactivate it before you go on. There are some rare cases, where the selection privation does not work (it happened to me twice) but I could not debug this.
Can you describe the situation where you would like the guideline being locked?
Using V. 1.4 (535) on MAC
I cannot move a guideline as you described Georg by selecting the whole line ! it only works as we previously did by selecting the guideline node itself.
The reason I’m asking for LOCK GUIDELINE feature is to prevent changing its position by mistake; this frequently happens when dargging + Shift[/b] to Select[b] several nodes where the guideline handle/node is included or it hides under other node !
Imagine that was a global Guideline which was shifted and you did not notice that … it may result reshaping allot of glyphs.
I will have a look at it.
Let me reuse this thread for report.
I think you know already, that I cannot undo any change of guidelines (movement, rotation, etc.). This also seems to prevent to go back to the states before it. Could you support guideline undo?
Thirded 
I vote for guideline undo. From time to time I accidentally move the guideline and undo would be very helpful.
The local guides should undo. Global guidelines are part of the font, but undo is glyph based. So I can’t add the changes to the undo of the glyph…
In that case, could you at least make it skip guideline undos and recover other changes?
Edit: Sorry, I noticed I can already.
I vote for lock guideline. Accidental move happens a lot to me. The undo global guides would be nice to…