[Users] firefox opens new copy of claws

[Dave Howorth]

I've noticed that for the past little while, whenever I click on a
mailto link in a web page, Firefox opens a new copy of claws-mail. I
don't want this.

Previously when I clicked on a mailto link, it simply opened a compose
window using my already open claws session. This is what I want.

I don't think I have knowingly changed any settings in either program.
FF is 68.2.0esr (64-bit) and claws is 3.16.0. OS is openSUSE Leap 15.0.

Does anybody have any idea why this is happening and/or on what I can
do to revert the behaviour?

TIA, Dave