How I can return false on button click if data was invalid? And dont overwrite user clipboard?

[jack-fdrv]

Expected behaviour Clipboard doesnt overwrite if after clicking on data user have missed some fields.

I thought that by going to the page '...' and pressing the button '...' then '...' would happen.
local sever

Actual behaviour

Instead of 'my clipboard before clicking have text, after clicking it should be there bc data not valid from fields', what I saw was that 'i can return only text or target, but i want return false and dont ovewrite clip board' happened instead.

[zenorocha]

Fixed at 7a5a910. Please use v1.5.10 in order to benefit from this.