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Modal keymap customization from an addon is not restored properly
Open, Confirmed, MediumPublic


System Information
Operating system: Win10
Graphics card: nVidia Quadro 600

Blender Version
Broken: 2.80 (sub 41), branch: master, commit date: 2019-01-22 16:54, hash: 25889423d324
Worked: unsure

Short description of error
It seems that if an addon makes a customization to a modal keymap, this customization only works until you restart blender. After restart, the keymap is not restored properly (left blank) and the only way to fix is to disable/re-enable the addon again.

Exact steps for others to reproduce the error

  • Install and Enable the attached .py addon
    • It adds a modal keymap for circle select (makes it so that circle select is active only if you hold down the C key)
  • Save Preferences
  • Notice that things work correctly. Circle select is only active while holding down the C key
  • Restart blender
  • Notice the keymap no longer works. Check the keymap in user preferences and notice that the new entry is actually blanked out



Event Timeline

The same issue happens when you define a complete new tool with a shortcut using bl_keymap. On first Add-on activation, the shortcut works. On restarting Blender, it is non-functional. But if you reload all scripts while Blender is still running, the shortcut works again. I have used this class from the Templates to verify this behavior:

bl_info = {
    "name": "Shortcutter",
    "author": "Bug Reporter",
    "version": (1, 0),
    "blender": (2, 80, 0),

import bpy
from bpy.types import WorkSpaceTool

class MyTool(WorkSpaceTool):

    # The prefix of the idname should be your add-on name.
    bl_idname = "my_template.my_circle_select"
    bl_label = "My Circle Select"
    bl_description = (
        "This is a tooltip\n"
        "with multiple lines"
    bl_icon = "ops.generic.select_circle"
    bl_widget = None
    bl_keymap = (
        ("view3d.select_circle", {"type": 'LEFTMOUSE', "value": 'PRESS'},
         {"properties": [("wait_for_input", False)]}),
        ("view3d.select_circle", {"type": 'LEFTMOUSE', "value": 'PRESS', "ctrl": True},
         {"properties": [("mode", 'SUB'), ("wait_for_input", False)]}),

    def draw_settings(context, layout, tool):
        props = tool.operator_properties("view3d.select_circle")
        layout.prop(props, "mode")
        layout.prop(props, "radius")

def register():
    bpy.utils.register_tool(MyTool, after={"builtin.scale_cage"}, separator=True, group=True)

def unregister():

if __name__ == "__main__":

Is this something that's on the ToDo list for 2.81 already? Or is there a workaround for it? Not being able to have modifier keys for custom tools limits the use quite a bit.

when will solve this problem? I can't advance because of it in my development

Hi @Max Derksen (Derksen) , if you are looking for a workaound for the problem of custom tools not working on Blender restart, you will find it in addons/mesh_snap_utilities_line/
A simplified version of it is in:
(Essentially, you would need to register the tool and keymap in some roundabout way)

@Shrinivas (Shrinivas) (Shrinivas) , thanks, I'll try this for the instrument. What about saving the shortcuts in the settings addon? that doesn't work either

@Max Derksen (Derksen) Maybe there is also an option for saving the shortcuts in the workaround. Just check in snap utilities.
I am an add-on developer and faced the same issue in my tool. I got the pointer about this workaround from one of the users (thanks @yoshiki nosaka (sakana3)).