How do I change the width of an operator popup?

FastStoneEditor1
I’v already tried with scale_x and ui_units_x but not working.
Here the code:

import bpy
class SimpleOperator(bpy.types.Operator):
    """Tooltip"""
    bl_idname = "object.simple_operator"
    bl_label = "Simple Object Operator"
    bl_options = {'REGISTER', 'UNDO'}
    #input value
    value: bpy.props.FloatProperty(
        name='Value',
        description='value description',
        default=0.05, soft_min=0.00, soft_max=.2, precision=4, step=.1, unit='LENGTH')
    def draw(self, context):
        layout = self.layout
        box = layout.box()
        #box.scale_x = 3.0 --> not working
        #box.ui_units_x = 300.0 --> not working
        box.prop(self, 'value')
    def execute(self, context):
        self.report({'INFO'}, 'Value: '+str(self.value))        
        return {'FINISHED'}
def menu_func(self, context):
    self.layout.operator(SimpleOperator.bl_idname)
def register():
    bpy.utils.register_class(SimpleOperator)
    bpy.types.VIEW3D_MT_object.append(menu_func)
def unregister():
    bpy.utils.unregister_class(SimpleOperator)
if __name__ == "__main__":
    register()

i don’t believe you can… the operator popup is a system panel, the “last operation panel”. have you seen this functionality in other addons/operators before? if so you might be able to reverse engineer what they’ve done to make it happen.

Thank you for reply.

I’ve seen effectively a larger panel in somewhere, but not coded.

It’s also a necessary feature because texts are all truncated. There is not option tu autoscale I’ve used developing for Cinema 4D.