Draw floating UILayout

Question

In sculpt mode you get this menu with a right click:

The UI elements in this menu are visually the same you would get by drawing a UI using bpy.types.UILayout functions. Yet, the only answers I found for drawing custom floating UI elements referred to bgl and blf, like in these two Blender StackExchange questions:

1. How to draw shapes in the node editor with python bgl
2. Floating UI window in 3D view

However, ideally I would use standard Blender UI elements to create something like that. Is there a way to draw standard Blender UI elements in floating windows like those in the screenshot using Python?

Answer 1

WindowManager.invoke_props_popup(operator, event)

Operator popup invoke (show operator properties and execute it automatically on changes)

Code based on How to call a confirmation dialog box?, I just replaced invoke_props_dialog by invoke_props_popup to diplay the popup without confirmation option:

import bpy

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

    prop1: bpy.props.BoolProperty()
    prop2: bpy.props.BoolProperty()

    @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_props_popup(self, event)

    def draw(self, context):
        row = self.layout
        row.prop(self, "prop1", text="Property A")
        row.prop(self, "prop2", text="Property B")


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):
        layout = self.layout
        layout.operator(SimplePropConfirmOperator.bl_idname)

def register():
    bpy.utils.register_class(OBJECT_PT_CustomPanel)
    bpy.utils.register_class(SimplePropConfirmOperator)

def unregister():
    bpy.utils.unregister_class(SimplePropConfirmOperator)
    bpy.utils.unregister_class(OBJECT_PT_CustomPanel)

if __name__ == "__main__":
    register()