Hi, 

I am using Inkscape to create patterns for myself and recently upgraded from .97 to 1.1.1. I just discovered this Measurement tool and if I can get it to work for me, it would be awesome. However, I work on a custom canvas size based on the patterns I am drafting and it is pretty big. So in the example pictured below my canvas is about 66" wide by 41" tall. (Sorry metric users, I'm an inches gal). The selection box around the red line is about 2x7 which is what I set it at when I created the line but when I apply the tool effect, you cannot see the number. I've maxed out the Font Size, played with orientation and units, nope, they stay ridiculously small. The word "TEST" is written using the text tool set at font size of 30pt. Then when I zoom in on the path effects to see the numbers, they are way off, this vertical angled line is showing over 133" when the selection box isn't even bigger than 8". I've tried messing with document scale, document canvas size defaults, and scale of the path effect, separately and together. I'm stuck I can't seem to get this to work. Am I missing something?

I get similar results by replicating your example. It seems the measurement is in pixels, but there is some rounding error that is involved as well.

Maybe there is another tool that is more user-friendly... Please describe in detail, what you hope the tool can do for you.

Sometimes I'm fine tuning a shape and I want to see how much adjustment I am making over all. I'm building sewing sloper patterns, so for example, this is actually the front of an armhole curve, if I were to move the center node to make the curve deeper I don't want the linear line between it and the endpoints to adjust more than say half an inch but since I'm really just fine tuning, I don't absolutely need it, it would just be nice to have it there and actively adjust as I move nodes around so I don't have constantly measure between them with the ruler tool. If there was a tool that actively measured the path itself, curved or straight that would even be better. Less math for me. For instance this curved line should measure exactly 8.625" inches along its curved path but I have to use the Extensions:Visualize Path:Measure Path which does measure but doesn't adjust if I change the shape so I don't know if I am staying within my limits, so I used the endpoints, nodes and angles, because I can use the ruler tool faster than running Measure Path. I sort of rambled, but I hope I was detailed enough as to what my goal was. 

The text size issue, I don't have a workaround for that.

The distance issue can be somewhat mitigated by using a scale of 0.0104 in the path effect settings. It has some rounding error, but may be useful for your application.

Thanks! That does help a little bit, not perfect, but it works for now. My screens are big enough, if I squint I can just make out the text of the number. 😄

Please file a bug report: https://inkscape.org/forums/beyond/how-to-report-bugs-or-request-new-features/