RT4 Usability issues with PRS and Power, Fan, Drum changes

My day job is in quality improvement in healthcare, mostly from a user-interface, human factors engineering perspective. There, bad interfaces injure and kill patients with the blame often incorrectly falling to the device user (look up device use errors in healthcare).

Channeling my human factors expertise to RT4 I note two new issues with the latest power, fan, PRS interface:


The most serious issue is the size and location of the PRS button. The PRS button is not a button that you want to accidentally hit, yet in the new interface it is between the - and + buttons: keys that you often need during a roast and that are easily undone if you hit the wrong one or hit one by mistake. It is too easy to hit PRS when you intend to hit +, - or Fan (above PRS).

Second, the new interface for power fan and drum changes adds extra (and unnecessary) cognitive complexity and steps. To make a change you have to tap Power, Fan, or Dum (or check to see if it is already selected), then press - or +. This adds a cognitive step and possibly and extra keypress. Having the same - and + keys for all three is an example of functional overloading, something the Bullet front panel suffers from even more, leading to things like the Sweet Maria’s cheat sheet–a sheet that should not be necessary with proper user interface design.

I believe that the new design might be a response to a complaint that the old -/+ buttons were too small, but that old design (with separate controls) is still preferable to the new one.


Oh wow… thanks for sharing this @toddjohnson. Because I haven’t been roasting in a while therefore not using the latest version of RT, that screen shot above has me concerned too. To use RT to change P/F/D now takes 2 clicks at minimum? And my twitchy fingers (I mean it) can easily involuntarily hit that PRS right there too if my mouse happens to be hovering there.

(In my past life I did financial trading software usability and QA testing, and I too had to deal with UI/UX issue - traders want as little mouse clicks as possible and want fast keyboard shortcuts because milliseconds count in real-time trading.)


If the control you want to change (P, F, or D) is already selected you can change it with just one click, but you have to visually check or remember the last selection. If you misremember, you run the risk of changing the wrong control. Fitts’ law tell us that bigger targets are faster to point to with either a mouse or finger (for touch). This depends to some extent on the origin of the mouse pointer (or your finger). If you are moving the mouse down to - or + they will be harder to hit since they are narrower vertically than horizontally. Of course bigger targets (PRS) near smaller ones are also more easily hit by error.

And visually - whether on the UI or a photograph - the bigger the “target” that’s where the human eye will naturally be drawn to first.


I’ll admit I haven’t been roasting for a week or so, so I haven’t noticed the change. I do know when and what I need, so it won’t be a problem to anticipate, but that’s me. Your concerns are all valid, and personally I’d like to see it back to normal sooner rather than later.

Hey @blacklabs and @toddjohnson,

Thank you both for your feedback. I’ve opened an internal ticket that we’ll use to track this. I’ll write back here when we have an update.


When I first saw this, I found it counter-intuitive. The big PRS button in-between the plus and minus buttons left me wondering: “If I click the plus or minus, am I clicking plus or minus for the PRS or the Power, Fan, and Drum?” I looked for help, but there was none.

My roasting laptop is not the most ergonomic setup and many times I find myself standing at the laptop which leads to that little mouse jump right before clicking.

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Something that I find annoying is:
When I am doing a playback, (this may happen at other times, but I haven’t run any recipes with the new update) the bar on the left hand side of the screen changes scale/resolution and is too tall to display all of the info. IF I slide it up, I can see the new Power/Fan/Drum, PRS + and - buttons, but then I can’t see the Total time at the top of the screen. If I slide the left sidebar down, then I can’t see the new adjustment buttons.
It appears to scale correctly to FIT automatically when I am not iin playback mode…

Edit: This is a former engineering laptop, so there is no issue with the lappy’s screen resolution and graphics adapter.

I’d like to add that removing the timer from the software part of things was not the greatest idea. I was looking for it incessantly until I’ve realised that I have to look at the machine, since it’s the only place I can find it. It isn’t good or comfortable having to shift focus from the software and look at the machine to be able to tell the exact time of the roast. And I don’t actually see some improvement that has taken its place.

I am running RoasTime v4.6.15 and when I am in the active roast is when the red outlined box shown below changes resolution and either hides the timer or hides the Power/Fan/Drum, PRS and + or - buttons. A slider bar appears and allows me to slide that part of the screen up or down.

I have a choice, I can either have the Timer showing, or the Power/Fan/Drum buttons showing, BUT not both at the same time.

I can see both before starting a playback, but once I start the playback the resolution for ONLY that area of the program changes

That’s even worse.

Before loading playback and overlay

After loading playback and overlay with the slider bar at the top.

With the slider bar at the bottom

Screen resolution

We will get this fixed, all info should be shown correctly at your resolution and scaling.

Thank you @jacob

The first and second crack timers have not been removed. They are shown on the left pane:

I meant the global timer which tells the time of roast, which I understood was just not being displayed because of scaling from billc’s post. As you’ve said above, the fix is on the way, so no worries. I just wanted to clear the misunderstanding.

Just saw this now.

Please add my vote for keeping PRS as far away from the other controls as possible (I recently fat fingered one of my recent roasts with the previous UI by absentmindedly clicking the PRS button instead of reducing power).

And for getting rid of the modality for adjusting power, fan, and drum.

But especially moving PRS where I can’t click it by mistake.

@jacob I’ve noticed that it was fixed, but I also wanted to say one other thing that I’ve seen, but forgot to mention and also forgot all about it when I was roasting. When you hide your taskbar the scrolling goes away and everything is displayed. So my question is, would it be possible to make the program go true fullscreen as videos, films, games…? There would be more space without scaling, and I don’t think anybody really needs their taskbar while roasting.

The second time I used my laptop (rather than the Bullet) to change a parameter, I accidentally ended the roast. I’m not sure how that happened, but I’ve since decided to never use the laptop to make changes again.

I changed the scale and layout setting to 100% (from 125%) and I don’t have the scaling issue that I originally reported.

I don’t know if Aillio fixed the problem or it was changing the scaling settings that fixed it.