BlenderPythonGuiHideSHowButton

import bpy

state = 1

class TestPanel(bpy.types.Panel):
    bl_label = "Test Panel"
    bl_idname = "OBJECT_PT_test"
    bl_space_type = "PROPERTIES"
    bl_region_type = "WINDOW"
    bl_context = "object"

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

        box = layout.box()
        if state==0:
            box.enabled=False
        box.label("Boite 1")
        box.operator("ops.bouton")

        box2 = layout.box()
        if state==1:
            box2.enabled=False
        box2.label("Boite 2")
        box2.operator("ops.bouton")

class Bouton(bpy.types.Operator):
    bl_idname = 'ops.bouton'
    bl_label = "Suite ..."
    bl_description = ""

    def execute (self, context):
        global state
        print(state)
        state = 1-state
        return {'FINISHED'}


def register():
    bpy.utils.register_class(Bouton)
    bpy.utils.register_class(TestPanel)


def unregister():
    bpy.utils.unregister_class(TestPanel)
    bpy.utils.unregister_class(Bouton)


if __name__ == "__main__":
    register()