（7）Blender源码分析之创建区域对象

在Blender的闪屏里，为了弹出一个子窗口，需要调用下面的函数来创建一个子窗口的区域：

uiPopupBlockHandle *ui_popup_block_create(bContext *C,

                                          ARegion *butregion,

                                          uiBut *but,

                                          uiBlockCreateFunc create_func,

                                          uiBlockHandleCreateFunc handle_create_func,

                                          void *ar