I haven’t got used to “relative” scaling of the palette yet, and I don’t think I ever will. For example, if I want to shrink something by 10% (i.e. I want 90% of the original), what number should I enter? Why do I have to do such a complex math and try & error to figure out the number?

As far as I remember, the reason for this is to make it easy to revert back to original simply by clicking the other button (+ for example), but doesn’t it distort the original form anyway? If I want to undo it, I just undo it. I don’t want a minus button that makes me stop and think (for a while).

Alternative solution is to allow X and Y scaling separately in the Transformation filter. How do you think?

Also: It would be great if the scaling in the Transformations panel allowed for more than one decimal. Scaling the font is often not just about playing around but sometines requires a very precise figure. I’d say about 6 digits would be appropriate.

Sorry, “absolute” means “fit to this size”, so it may be more appropriate to call it relative? The current implementation is, I don’t know, proportional?

It is the reverse of the upscale, so you calculate 1000 divided by resulting percentage, and you have the percentage you need to enter. E.g. you want to scale down to 90%, so you enter (1000/90=) 11.1, and press the minus button.

The idea is that you can use plus and minus buttons as each other’s reverse.

I still maintain that it’s very unintuitive. The main problem seems to be the unit (%) that this box is using and the minus button (is it necessary?). Reducing something by 100% should NOT result in half. In fact I don’t understand what’s going on even in the upscaling. Assuming I have a 1000*1000 square, I type:

10% and + to get a 11001100 square. Okay, that’s 10% increase.
200% and + to get 30003000. Why is it not 20002000?
500% and + to get 60006000. Why not 5000*5000?

10% and - to get a 910909. What happened?
200% and - to get 334333. What?
300% and - to get 250*250. Why?

It makes sense to me only in a small amount of upscaling, but in many cases it’s too difficult. I tried to reduce it down to 75%, so I did the calculation (1000/75=13.333…), applied minus, and I got 882*883 square. It doesn’t seem to be working. After some trial and error, I found that the “correct” percentage is 33.3 which I have no idea how I can get by calculation (and as Tim says, not accurate enough).

I now know that I can do math in the info box, but this alternate solution is not apparent compared to the buttons, and you have to happen to know it. From the UI standpoint, I think it’s better that palette supports the traditional logic too (preferably by default in order to not confuse beginners). And the whole-font scale too.

The differences between 909 and 910 or 334 and 333 are rounding errors due to the position of the object and the grid precision you set in Font Info > Other Settings.

Calculating with percentages is confusing for people either way. And I can confirm people using minus/plus as reverses of each other. Ask 100 people on the street what should be the result when they subtract 10% from 100, then add 10% again, you will hear ‘100’ as an answer more often than you’d think.

The question is, how can both methods be implemented side-by-side? A possible way out could be the number field accepting negative numbers (it doesn’t at the moment), and the Plus button with a negative number would yield the expected downscale. And perhaps instead of plus/minus it should be bottom left and top right arrow.

I can imagine those, but they simply misunderstand the logic. My arguments are,
1. Do you really support that misunderstanding? Also, if you ask 100 people on the street to subtract 33.333% from 100, how many people answer as 75 as opposed to 67.777? Zero, I assume.
2. How often do you subtract and increase again but not use undo in practice, especially when you know that there will be a rounding error?
3. I set grid spacing to 1 all the time, which I assume most users do as well. Do I need to set it to 0 to make those scaling buttons work every time? (Okay, this is an accuracy issue.)
Not side by side, but how about making both selectable from a pulldown menu? I propose that the minus button is not necessary. If the field accepts negative values (which I want), then the existence of minus button doesn't make sense. Also the top tight and bottom left arrow probably doesn't make sense as they imply scaling direction (i.e. confusing with origin point setting).

I need a third option because I would likely answer 66.777…, not 67.777…

Glyphs stores the original coordinates. So hitting plus plus plus, and then minus minus minus should yield the exact same coordinates again.
If I do a lot of scaling (and especially if you scale the whole font), of course I will either set it to 0, or I will set the subdivision to 100, which usually is good enough.
This just gave me an idea. How about a Reverse button and a Scale button, and the ability to enter negative values? Then it should be clear to everyone. The Reverse button could have a circled arrow, similar to the Refresh button in Font Info > Features. The Scale button could look like the double arrows OS X uses for full screen mode. You could enter -10% and press Scale to get the mathematically correct percentage calculation, or 10% and Reverse to apply the current method. How about that?

I had the same idea about a negative scale button. It works. I might even add 100% to the value so that you enter 75% and hit the “+” button to scale it down. So we the renaming would get rid of most of the confusion.

Does anyone has a good abbreviation for “scale” and “reverse”?

For those of us with decades of experience in the graphic arts, a percentage value means just one thing and does not require negative numbers to be intuitive. Just enter the value in the field and hit “Return” or click a calculate button.

Perhaps best would be to have a Preferences setting so Users would have a choice. If you did that you would not need to change the current method, merely add the traditional method. For that you don’t need the Minus button or negative values, just change the Plus button to Multiply, and enable using the Return key in lieu of clicking the button.

As for abbreviations, I cannot come up with any, so how about just “S” and “R” or “Sc” and “Rv”?

Good idea. Put in the target percentage and you don’t need to calculate in your head. Default value 100%, so things are clear.

I would still prefer an icon over an abbreviation. Another idea for the scale button: small, medium and big square on top of each other, bottom left aligned.