Discovered in the QA of T329493.

In T329493#9863795, @dom_walden wrote:

I found a few issues which I don't think are urgent:

• It is possible to press the buttons by clicking to the right of them, as far as the end of the containing form.

This is caused by the functionality of the buttons being implemented through an event listener on the form field. This for OOUI interfaces means that a box around the field is selected and responds to click events with the space to the right being noticeable. Instead the event listener should be attached to the button so that clicking elsewhere does not cause unintended side-effects, which may be especially noticeable if using a mobile device.

Steps to reproduce

1. Log into an account with the sysop group
2. Open Special:CheckUser and select the Get users check type
3. Run a check on an IP or IP range
4. Scroll to the bottom of the results to find the block form
5. Click to the right of one of the Block selected IPs or Block selected accounts buttons

What happens
A Special:InvestigateBlock page is opened in a new tab

What should have happened
Nothing should have happened as the button was not clicked