gtktextbuffer tag

Problem description: I would to like to apply weight tag to some selected portion of text buffer and again same weight tag need be applied to some other selected area in same buffer. But at that time weight tags are getting changed both in previous text area and newly selected area. But I want weight tag to be applied only to n开发者_如何学编程ewly selected area and not to he previous area were weight tag is had been already applied. EX: step 1->aaabbbccc--> this is my text and i will apply tag weight to selected area "aaa" to bold. step 2-> now apply weight tag to area "ccc" ...but now both area "aaa" and "ccc" is getting changed as per the value of weight tag.but want only 'ccc' need to be changed.

Could anyone give me any solution for above problem ?

Use different tag objects to apply to the different regions.