Wow... I was at most expecting an explanation for the tool behavior, was not definitely expecting a detailed tutorial! Excellent job, I hope others with similar problems will find this also. Thanks!

Thanks for the tip, it does work as I needed with arcs, but the problem remains for rectangles or other non-regular shapes.

Well, I need the corner of the bottom edge of the shape (the arch, in my case) to touch a line.

Of course I could measure the ratio by hand, but it won't give accurate enough results so that the corner is exactly on the line. That's why I was hoping this tool would do it for me. When I tried the scale tool in normal mode, it does not snap correctly to the other edge, even if I put a guide point or an endpoint there. The little yellow box does snap to an endpoint, but it doesn't correlate with behavior of the scale tool, ie. it ignores the snap target completely and scales in freeform.

The arch is 1 meter by 10 meters, not 1 millimeter by 10 millimeters.
And I don't think it's the scale that matters, nor that it's 2D. I started a blank sketchup and recreated the same arch at the same size, 1m by 10m and the scale tool refused to use any point as origin except points in a direct line above the selected handle.
Then I copied and scaled the same arch by a factor of 10, so it was now 10 by 100 and the scale tool behaved exactly the same.

Then I made a rectangle of the same size and the scale too still didn't work, so I extruded it to a box and tried to pick the corner handles for the scale tool, but again the scale tool didn't work.

However, if I shrink the same arch/rectangle/box so that it's ratio of edges is more close 1 by 4 example, the tool allows me to pick some points below the selected handle, but not all the way down.

As I see it, it should not matter for the scale tool where I choose the origin and target points, since all it needs is the distance and direction between to translate it to a scale factor for the selected entity.

I've attached an image that better shows the problem I'm experiencing. The yellow area highlighted is the zone where the tool refuses to work. Every point outside this zone is operable. The rectangle is about 35 by 22 meters in size. The invalid zone border is about 4 meters.

Hello there!

First I want to thank Fredo6 for the awesome plugin, but I've hit a problem with scale to target tool.
I'm trying to scale a small filled arch (1m by 10m) along the flat to hit an edge near it. Once I doubleclick the correct corner to activate the target scaling, I can't select any point for origin.
The funniest thing is, that if I scale the arch bigger by other methods, I'm able to select some points to use as origin.
Is there some sort of minimum size requirement for the scale to target tool? What am I doing wrong here?