It worked perfectly. Thank you so much!!

Thank you so much for this suggestion. I checked it out and it seems to be exactly what I needed. I will try it out soon and let you know if it worked.

But by doing that, I will still have the option of going to the file menu and then clicking save.
The extension I've made is actually an encryption method, and I don't want anyone who uses the file to be able to save it without encrypting it.

That's unfortunate but thank you so much for letting me know.
If disabling is not possible for native items, is it possible to trigger my extension when the save button is clicked?
The reason is I need my extension to be run just before I save and close a sketchup file.

Hey guys!!
I have just started making extensions for sketchup using Ruby. I wanted to know if there was anyway, maybe using a ruby code, that I can disable an existing menu item. I actually need the Save and Save as options in the file menu to get disabled or grayed when the extension I've designed, is run.
From all the research I've done, I've only seen a way to add a menu item and then disable or gray the added item using "MF_GRAYED". But I wanted to do this to already existing menu item.
Please kindly help me if this is possible.
Thankyou.