a contextual menu for the font overview that adds an alternate glyph next to the default glyph

makeAlternatesMenu.py

from mojo.events import addObserver
import ezui
from mojo.subscriber import Subscriber, registerFontOverviewSubscriber
from mojo.UI import CurrentFontWindow

class alternatesController(ezui.WindowController):

    def build(self, parent):
        
        content = """
        Note:
        [[_ _]]    @textEditor
        """
        self.parent = parent
        self.font = CurrentFont()
        self.copy = ".alt"
        self.referenceLayer = "AltReference"
        self.selection = self.font.selectedGlyphs
        
        descriptionData = dict(
            textEditor=dict(
                value=self.copy,
                ),
        )

        self.w = ezui.EZPopover(
            size=(200, 150),
            content=content,
            descriptionData=descriptionData,
            parent=parent,
            behavior="transient",
            controller=self
        )
        self.w.bind("will close", self.windowWillClose)
                
    def getWindowCenterPos(self):
        x,y,w,h = self.parent.getPosSize()
        xc = (w/2) + x
        yc = (h/2) + y
        return (xc,yc)

    def openWindow(self):
        x,y = self.getWindowCenterPos()
        self.w.open(location=(x, y, 1, 1))
        
    def textEditorCallback(self,sender):
        self.copy = sender.get()
        
    def windowWillClose(self,sender):
        suffix = self.copy
        if not suffix.startswith("."):
            suffix = f".{suffix}"

        if self.selection:
            for glyph in self.selection:
                altName = glyph.name + suffix
                if altName in self.font.keys():
                    pass

                self.font.newGlyph(altName)
                altGlyph = self.font[altName]
                altGlyph.clear()
                altGlyph.appendGlyph(glyph)
                altGlyph.width = glyph.width
                altGlyph.unicode = None

                # copy to refernce layer
                if self.referenceLayer not in self.font.layerOrder: self.font.newLayer(self.referenceLayer)
                altGlyph.copyToLayer(self.referenceLayer, clear=True)
                mask = altGlyph.getLayer(self.referenceLayer)
                mask.width = altGlyph.width

                # move alternate next to default
                order = list(self.font.templateGlyphOrder)
                place = (order.index(glyph.name)) + 1
                order.insert(place, order.pop(-1))
                self.font.templateGlyphOrder = order



class makeAlternatesMenu(Subscriber):
    
    def build(self):
        pass

    def fontOverviewWantsContextualMenuItems(self, info):
        myMenuItems = [
            ("Make alternate(s)...", self.makeAlternates),
        ]
        info["itemDescriptions"].extend(myMenuItems)
    
    def makeAlternates(self,sender):
        w = CurrentFontWindow()
        self.altController = alternatesController(w.window())   
        self.altController.openWindow()


        
if __name__ == "__main__":    
    registerFontOverviewSubscriber(makeAlternatesMenu)