ui.gadgets.panes: fix for big strings on windows and linux.
ui.gadgets.panes: fix for big strings on windows and linux.

Using 3639 grapheme length, which is win32 limit. Maybe cairo supports
4681 graphemes, but use the lower limit for now.

AlexIljin/factor,bpollack/factor,AlexIljin/factor,tgunr/factor,bpollack/factor,tgunr/factor,AlexIljin/factor,bpollack/factor,mrjbq7/factor,AlexIljin/factor,tgunr/factor,tgunr/factor,mrjbq7/factor,AlexIljin/factor,bpollack/factor,bpollack/factor,factor/factor,mrjbq7/factor,factor/factor,factor/factor,tgunr/factor,factor/factor,tgunr/factor,mrjbq7/factor,factor/factor,mrjbq7/factor,bpollack/factor,AlexIljin/factor,factor/factor,mrjbq7/factor,AlexIljin/factor,bpollack/factor