Either I seem to have a problem in the code? or this is just the limitations of the button?

The code breaks when you use ' or "

The button either doesn't show up and the code all shows up if you use it in spoiler= (here) or the button shows up but doesn't work when you click it when you enter it ](here)[/spoiler

I don't recommend using this, because it can be exploited to run JavaScript of the user's choice.

[spoiler=' + document.cookie + ']Example of a possibility[/spoiler]

or

[spoiler='); window.open('http://www.annoyingadsite.com]click here[/spoiler]

i am still wondering how we could add this to the vbcode buttons

same here

no one can make this into a button
so people can just click on it?