Drop-down list

I am pretty new to mozilla add ons development . Can you tell me how to create a drop-down menu kind of thing of all tabs.

It depends on where you want this drop down to be. If it’s part of a toolbar button, you could use the SDK or even WebExtensions. I suggest you start here.

@jorgev - I went through all the tutorials and i have a fair idea of add-ons development . My question is which component of sdk ( like button , panel etc ) should i use to get a drop-down list of all active tabs.

I think you’ll need a toggle button with a panel, and use the tabs API to get the list. The contents of the panel would be custom HTML you write.