fix #3515: crash in about
fix #3515: crash in about
cgeo/cgeo,brok85/cgeo,Huertix/cgeo,Huertix/cgeo,tobiasge/cgeo,ThibaultR/cgeo,lewurm/cgeo,Bananeweizen/cgeo,marco-dev/c-geo-opensource,schwabe/cgeo,kumy/cgeo,S-Bartfast/cgeo,KublaikhanGeek/cgeo,cgeo/cgeo,auricgoldfinger/cgeo,S-Bartfast/cgeo,schwabe/cgeo,rsudev/c-geo-opensource,KublaikhanGeek/cgeo,pstorch/cgeo,lewurm/cgeo,kumy/cgeo,samueltardieu/cgeo,ThibaultR/cgeo,rsudev/c-geo-opensource,brok85/cgeo,superspindel/cgeo,SammysHP/cgeo,vishwakulkarni/cgeo,matej116/cgeo,matej116/cgeo,cgeo/cgeo,schwabe/cgeo,lewurm/cgeo,pstorch/cgeo,auricgoldfinger/cgeo,vishwakulkarni/cgeo,S-Bartfast/cgeo,pstorch/cgeo,samueltardieu/cgeo,mucek4/cgeo,SammysHP/cgeo,schwabe/cgeo,marco-dev/c-geo-opensource,cgeo/cgeo,xiaoyanit/cgeo,yummy222/cgeo,Bananeweizen/cgeo,brok85/cgeo,superspindel/cgeo,mucek4/cgeo,yummy222/cgeo,yummy222/cgeo,KublaikhanGeek/cgeo,Huertix/cgeo,vishwakulkarni/cgeo,Bananeweizen/cgeo,xiaoyanit/cgeo,mucek4/cgeo,SammysHP/cgeo,tobiasge/cgeo,samueltardieu/cgeo,rsudev/c-geo-opensource,kumy/cgeo,xiaoyanit/cgeo,auricgoldfinger/cgeo,tobiasge/cgeo,madankb/cgeo,marco-dev/c-geo-opensource,ThibaultR/cgeo,madankb/cgeo,madankb/cgeo,matej116/cgeo,superspindel/cgeo