How to use <checkbox> element in the extension pref page?

[117649]

I'm trying to make a pref page for an bootstrap extension but <checkbox> elements just won't display at all, so does the label of the buttons.
What I'm missing here?

[xiaoxiaoflood]

Without further info I can't say.

But please, note that this is not a place for general support about legacy extension development, I suggest you to ask these things here:
http://forums.mozillazine.org/viewforum.php?f=19

Almost all legacy addons in this repository use checkbox customElement, so you can read and play with the codes, but you should probably use <input type="checkbox> instead.