open your url address write in it about:config then write picture in search button find for dom.image.picture.enabled make it true

After i updated my firefox browser a can't save pictures anymore.

What prevents you from saving pictures?

I use a mouse on my tablet when i try to save a picture it does not work.the menu does not show

Is this an Android tablet and are we talking about Firefox for Android?

Yes and yes

Can you save pictures without the mouse, i.e. when just using the normal touch interface?

Yes i can

Then I don't think I can help any more. You may contact support for the vendor of your mouse. Also, it isn't entirely clear to me why anyone wants to use a mouse for a touch device. If a mouse is important for you, a different device than an Android tablet may suit your needs better.

I am in a wellchair.the problem is solved.