import bpy
from bpy.props import BoolProperty

class LayoutDemoPanel(bpy.types.Panel):
    bl_label = "Demo Panel"
    bl_space_type = 'VIEW_3D'
    bl_region_type = 'UI'

    def draw(self, context):
        layout = self.layout

        wm = context.window_manager # Our bool is in the windows_manager
        layout.prop(wm, "deselect_bool") # Our checkbox

def register():
    bpy.types.WindowManager.deselect_bool = bpy.props.BoolProperty(
    name="Checkbox", description="A checkbox", default = False)
    bpy.utils.register_module(__name__)

def unregister():
    del bpy.types.WindowManager.deselect_bool # Unregister our flag when unregister.
    bpy.utils.unregister_module(__name__)

if __name__ == "__main__":
    register()