The functionality shown in the video below was first introduced in ZBrush 2021.6, the latest release earlier this month.
It is noted that the Sticky Keys system from ZBrush 2021.6 is now disabled by default. Sticky Keys allows you to hold down any hotkey that triggers a slider in the ZBrush interface, move the cursor to adjust that slider, and then release the hotkey.
This system was designed to reduce the number of mouse clicks required to perform common tasks, but some users have reported that it causes the sliders to not work correctly.
In the ZBrush 2021.6.1 update Pixologic added the ability to change the amount of time you have to hold down a hotkey to start a new process, while in this ZBrush 2021.6.2 update it is disabled by default.
ZBrush 2021.6.2 is available for 64-bit Windows Vista and above and Mac OS X 10.11 and above. The cost of the new perpetual licence is $895. Subscription costs $39.95 per month or $179.95 for six months. The upgrade is free for existing users.