fix gui slider bug in win8
fix gui slider bug in win8

lheric/GitlHEVCAnalyzer,lheric/GitlHEVCAnalyzer,lheric/GitlHEVCAnalyzer,linqiaozhou/GitlHEVCAnalyzer,linqiaozhou/GitlHEVCAnalyzer,linqiaozhou/GitlHEVCAnalyzer