Call a Dialog Box upon toggling boolean/checkbox in the UI

Question

I want to make sure that the user acknowledges the selection of a checkbox. What am I missing?

import bpy
from bpy.types import PropertyGroup

def my_boolean_handler(self, context):
    #context.window_manager.invoke_popup(self) # error self should be an operator
    bpy.ops.my_category.custom_confirm_dialog() # prints Info: YES! because executed not invoked

class MySettings(PropertyGroup):
    my_boolean : bpy.props.BoolProperty(
        name = "My Boolean",
        description = "This checkbox triggers a Dialog Box",
        default = False,
        update = my_boolean_handler
    )

class SimpleConfirmOperator(bpy.types.Operator):
    """Really?"""
    bl_idname = "my_category.custom_confirm_dialog"
    bl_label = "Do you really want to do that?"
    bl_options = {'REGISTER', 'INTERNAL'}

    @classmethod
    def poll(cls, context):
        return True

    def execute(self, context):
        self.report({'INFO'}, "YES!")
        return {'FINISHED'}

    def invoke(self, context, event):
        return context.window_manager.invoke_confirm(self, event)
    

class OBJECT_PT_CustomPanel(bpy.types.Panel):
    bl_label = "My Panel"
    bl_idname = "OBJECT_PT_custom_panel"
    bl_space_type = "VIEW_3D"   
    bl_region_type = "UI"
    bl_category = "Tools"
    bl_context = "objectmode"

    def draw(self, context):
        settings = context.scene.world.my_settings
        layout = self.layout
        layout.prop(settings, 'my_boolean')

def register():
    bpy.utils.register_class(OBJECT_PT_CustomPanel)
    bpy.utils.register_class(SimpleConfirmOperator)
    bpy.utils.register_class(MySettings)
    bpy.types.World.my_settings = bpy.props.PointerProperty(type=MySettings)
    

def unregister():
    del bpy.types.World.my_settings
    bpy.utils.unregister_class(SimpleConfirmOperator)
    bpy.utils.unregister_class(OBJECT_PT_CustomPanel)

if __name__ == "__main__":
    register()

I saw 2 StackExchange questions pointing in the right direction, but couldn't get it working with the checkbox.

• How to call a confirmation dialog box? (most code example from here)
• Call a Dialog Box without 'OK' confirmation button?

Answer 1

The simple answer is in the first Q&A you linked to. Simply modify the 6th line to

bpy.ops.my_category.custom_confirm_dialog("INVOKE_DEFAULT")

However AFAIK calling operators in property callbacks methods is unsupported. It means that it works but it shouldn't. You can see the problem here, the confirmation dialog does get displayed, but since Blender registered that you clicked the mouse on the property, when you release the mouse button it immediately validates the confirmation dialog, making it almost useless.

I would advise using another method, which gets rid of the callback method and uses the operator directly to modify the property value.

You need to set the layout.operator_context beforehand though, so the operator knows to display the confirmation dialog.

import bpy
from bpy.types import PropertyGroup


class MySettings(PropertyGroup):
    my_boolean : bpy.props.BoolProperty(
        name = "My Boolean",
        description = "This checkbox triggers a Dialog Box",
        default = False,
    )

class SimpleConfirmOperator(bpy.types.Operator):
    """Really?"""
    bl_idname = "my_category.custom_confirm_dialog"
    bl_label = "Do you really want to do that?"
    bl_options = {'REGISTER', 'INTERNAL'}

    @classmethod
    def poll(cls, context):
        return True

    def execute(self, context):
        context.scene.world.my_settings.my_boolean = not context.scene.world.my_settings.my_boolean
        [a.tag_redraw() for a in context.screen.areas]
        return {'FINISHED'}

    def invoke(self, context, event):
        return context.window_manager.invoke_confirm(self, event)
    

class OBJECT_PT_CustomPanel(bpy.types.Panel):
    bl_label = "My Panel"
    bl_idname = "OBJECT_PT_custom_panel"
    bl_space_type = "VIEW_3D"   
    bl_region_type = "UI"
    bl_category = "Tools"
    bl_context = "objectmode"

    def draw(self, context):
        settings = context.scene.world.my_settings
        layout = self.layout
        layout.prop(settings, 'my_boolean')
        layout.operator_context = "INVOKE_DEFAULT"
        layout.operator("my_category.custom_confirm_dialog", text="Toggle My Boolean")

def register():
    bpy.utils.register_class(OBJECT_PT_CustomPanel)
    bpy.utils.register_class(SimpleConfirmOperator)
    bpy.utils.register_class(MySettings)
    bpy.types.World.my_settings = bpy.props.PointerProperty(type=MySettings)
    

def unregister():
    del bpy.types.World.my_settings
    bpy.utils.unregister_class(SimpleConfirmOperator)
    bpy.utils.unregister_class(OBJECT_PT_CustomPanel)

if __name__ == "__main__":
    register()

You'll notice the interface doesn't get updated when you confirm the dialog box. You can force a redraw with [a.tag_redraw() for a in context.screen.areas].

Answer 2

Here's what I was able to do based on Gorgious answer:

It looks like a boolean but is not. It is a checkbox with an operator that is hidden under the label. For my liking solution is too hacky and it seems that it is not intended for what I want it to be.

Here is the source code:

import bpy
from bpy.types import PropertyGroup

def boop(self, context):
    context.scene.world.my_settings.my_boolean = not context.scene.world.my_settings.my_boolean

class MySettings(PropertyGroup):
    my_boolean : bpy.props.BoolProperty(
        name = "",
        description = "This checkbox triggers a Dialog Box",
        default = False,
    )


class SimpleConfirmOperator(bpy.types.Operator):
    """Really?"""
    bl_idname = "my_category.custom_confirm_dialog"
    bl_label = "Do you really want to do that?"
    bl_options = {'REGISTER', 'INTERNAL'}

    @classmethod
    def poll(cls, context):
        return True

    def execute(self, context):
        context.scene.world.my_settings.my_boolean = not context.scene.world.my_settings.my_boolean
        [a.tag_redraw() for a in context.screen.areas]
        return {'FINISHED'}

    def invoke(self, context, event):
        return context.window_manager.invoke_confirm(self, event)
    

class OBJECT_PT_CustomPanel(bpy.types.Panel):
    bl_label = "My Panel"
    bl_idname = "OBJECT_PT_custom_panel"
    bl_space_type = "VIEW_3D"   
    bl_region_type = "UI"
    bl_category = "Tools"
    bl_context = "objectmode"

    def draw(self, context):
        settings = context.scene.world.my_settings
        layout = self.layout
        row = layout.row(align=True)
        row.prop(settings, 'my_boolean')
        row.operator_context = "INVOKE_DEFAULT"
        row.operator("my_category.custom_confirm_dialog", text="Toggle My Boolean                     ", depress=True, emboss=False)

def register():
    bpy.utils.register_class(OBJECT_PT_CustomPanel)
    bpy.utils.register_class(SimpleConfirmOperator)
    bpy.utils.register_class(MySettings)
    bpy.types.World.my_settings = bpy.props.PointerProperty(type=MySettings)
    

def unregister():
    del bpy.types.World.my_settings
    bpy.utils.unregister_class(SimpleConfirmOperator)
    bpy.utils.unregister_class(OBJECT_PT_CustomPanel)

if __name__ == "__main__":
    register()