Sketcher/UI/UX: Problem with informing about the fillet/champfer algorithm on "rounded" lines (arcs/B-spline)

Is there an existing issue for this?

• I have searched the existing issues

Problem description

I've opened Sketcher thousands of times, but only today did I learn that non-straight lines can be connected using a chamfer and fillet. And the most interesting thing is that many of my friends who use FreeCAD didn't know about this. In other words, they've been using workarounds for these actions for years.

The problem is that chamfer and fillet don't apply to single vertices. Specifically, a single click is used most often (because it saves actions). Even though the tooltip specifies a single vertex, it doesn't work.

What's even stranger is that the tool doesn't work without displaying any warning. It simply does nothing when you click on a vertex.

https://github.com/user-attachments/assets/ff6c2819-5e26-46e2-9640-b6d1f2a245a9

A good example is constraint symmetry. If an incorrect action is taken, a window appears informing the user of the correct procedure.

https://github.com/user-attachments/assets/f3ba9e89-db94-4a1a-9203-7ef34641d920

So, the solution to the problem might look like this:

1. Make it possible to create a chamfer/fillet in the same way as for straight lines (clicking on a common vertex).
2. If point 1 is impossible, implement a tooltip that displays text indicating that the user should click on the line itself, not the vertex.

After the user sees the message a couple of times, they will know for sure that clicking on a single vertex for curved lines is not recommended.

I think point 2 is very easy to implement.

Furthermore, I believe such a message should be displayed for all similar cases where it's unclear why something isn't working.

Full version info

OS: Manjaro Linux (KDE/plasma/xcb)
Architecture: x86_64
Version: 1.1.0dev.14555 (Git shallow) AppImage
Build date: 2025/10/07 22:49:55
Build type: Release
Branch: main
Hash: 68f083a6d169ec523fa9d46b7cc40addb1e4ffbe
Python 3.11.13, Qt 6.8.3, Coin 4.0.3, Vtk 9.3.1, boost 1_86, Eigen3 3.4.0, PySide 6.8.3
shiboken 6.8.3, xerces-c 3.3.0, IfcOpenShell 0.8.2, OCC 7.8.1
Locale: Russian/Russia (ru_RU)
Navigation Style/Orbit Style/Rotation Mode: Revit/Turntable/Drag at cursor
Stylesheet/Theme/QtStyle: OpenLight.qss/OpenLight/
Logical DPI/Physical DPI/Pixel Ratio: 96/91.7938/1
Installed mods: 
  * addFC-main 1.6.2
  * Reinforcement
  * SvgWorkbench-main 1.0.0.dev5
  * PitchedRoof
  * LyapinWorkbrench
  * FreeCAD_FastenersWB-master 0.5.42
  * FreeCAD_SketchArch-master
  * FrameForge 0.1.5
  * Road 2025.2.22
  * Curves 0.6.70
  * freecad.gears 1.3.0
  * CurvedShapesWorkbench-master 1.0.13
  * Silk 0.2.0
  * sheetmetal 0.7.55
  * OpenTheme 2025.5.20
  * Manipulator-master 1.6.3
  * FreeCAD_ThreadProfile-master 1.97.0

Subproject(s) affected?

Sketcher

Anything else?

No response

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