Script python code to apply RMX Tuner to selected Glyphs

Is it possible to apply RMX Tuner filter to slant some glyphs using python?
I have tried coding it like so with the help of Chat GPT:

# Import the necessary modules
from GlyphsApp import *
from GlyphsApp.plugins import *

# Access the current font and the selected glyphs
font = Glyphs.font
selected_glyphs = [x.parent for x in font.selectedLayers]

# Iterate through all masters in the font
italic_masters = []
for master in font.masters:
    # Check if the master's font name contains 'italic'
    if 'italic' in

# Print all masters with 'italic' in their name
print("Italic masters:", ", ".join(italic_masters))

# Proceed with applying the RMX Tuner filter
for master in font.masters:
    if 'italic' in
        # Create an RMX Tuner filter instance
        rmx_tuner_filter = NSClassFromString("RMXFilter").alloc().init()
        # Configure the RMX Tuner filter settings
        rmx_tuner_filter.settings = {
            'RMXFilterPreset': 'RMX Tuner',
            'angle': 10
        # Apply the RMX Tuner filter only to selected glyphs in the master
        for glyph in selected_glyphs:
            layer = glyph.layers[]
            rmx_tuner_filter.processLayer_withArguments_(layer, None)
        # Print a message to indicate the filter has been applied
        print("RMX Tuner filter applied to selected glyphs in master:",

But it doesn’t work. Here’s the original prompt with what I want to do in plain English:
– In Glyphs App scripting, I want to apply RMX Tuner filter to all Masters containing italic in its fontName with a slant value of 10 only on selected Glyphs.