Here's a sketch:

import ezui

class CornerTools(ezui.WindowController):

    def build(self):
        content = """
        * TwoColumnForm      @mainForm
        > : Treatment:
        > (X) Break          @treatmentRadios
        > ( ) Build
        > ( ) Pit
        > : Radius:
        > ---X--- [__]       @radiusSlider
        > : Roundness:
        > ---X--- [__]       @roundnessSlider
        ---
        """
        footer = """
        No corners selected. @statusLabel
        (Apply)              @applyButton
        """
        
        descriptionData = dict(
            mainForm=dict(
                titleColumnWidth=72,
                itemColumnWidth=200
            ),
            statusLabel=dict(
                gravity='leading',
            )
        )
        self.w = ezui.EZWindow(
            title='Corner Tools',
            content=content,
            descriptionData=descriptionData,
            footer=footer,
            controller=self
        )

    def started(self):
        self.w.open()

CornerTools()

Sorry for the noise, I am not sure my comment to a closed issue will stay on the radar – for awareness’ sake, here it is again:

The fix to #2 breaks the non-interactive corner rounding in the following way:
https://www.dropbox.com/s/7p2g739i9vt5i1f/corner.mov?dl=0

Could benefit from Merz.

Upon zoom, the drawings are a bit blurry. This is especially noticeable in Preview mode.

I think this can be achieved with registerExtensionDefault. I will make a PR when I have a chance. Let me know any thoughts.

Getting this message in the output window upon every RF open.

********************
Installing 'CornerTools' report:
  /Applications/RoboFont-4_4b2.app/Contents/Resources/lib/python3.9/fontTools/misc/py23.py:13: DeprecationWarning: The py23 module has been deprecated and will be removed in a future release. Please update your code.

********************

With this extension installed while working in single-window mode, clicking things in the font overview causes the focus to get stuck there. This happens even when the tool isn't activated.

For example, if I click a glyph in the font overview to edit a glyph, and then click somewhere in the glyph view to move the focus there, hitting a number key on my keyboard doesn't activate the corresponding tool as expected, but instead opens the glyph for that number, as though I had never clicked away from the overview.

Or, if I select a point in the glyph view and try to move it up with my arrow key, I just get taken to the glyph that is above the current glyph in the font overview grid.

Nothing shows up in the output or the log file when it happens, but installing the extension returns the behavior to normal.

I get this in RF3:
Could not download the extension zip file for: 'CornerTools'

... would be helpful to understand the result.

And maybe also off-curves.

Related: #9

Using a simple shape like an /H I'm getting this error if I accidentally slide too far (in my example, when I go above 85 radius), and then the traceback wont go away and keeps printing if I change anything.

Here's the full traceback:

Traceback (most recent call last):
  File "lib/eventTools/eventManager.pyc", line 131, in callObserver_withMethod_forEvent_withInfo_
  File "cornerToolController.py", line 89, in setControls
  File "cornerToolController.py", line 121, in makePreviewGlyph
  File "cornerToolController.py", line 129, in makeCornerGlyph
  File "cornerToolController.py", line 157, in breakCorners
  File "/Users/cjdunn/Library/Application Support/RoboFont/plugins/CornerTools.roboFontExt/lib/glyphObjects.py", line 1502, in breakCorner
IndexError: pop index out of range​

Thanks!

Example image:

Example glyph:

<?xml version="1.0" encoding="UTF-8"?>
<glyph name="H" format="2">
  <advance width="450"/>
  <outline>
    <contour>
      <point x="53" y="0" type="line"/>
      <point x="136" y="0" type="line"/>
      <point x="136" y="366" type="line"/>
      <point x="314" y="366" type="line"/>
      <point x="314" y="0" type="line"/>
      <point x="397" y="0" type="line"/>
      <point x="397" y="750" type="line"/>
      <point x="314" y="750" type="line"/>
      <point x="314" y="439" type="line"/>
      <point x="136" y="439" type="line"/>
      <point x="136" y="750" type="line"/>
      <point x="53" y="750" type="line"/>
    </contour>
  </outline>
</glyph>