Fixed mouse dragging bug.
Fixed mouse dragging bug.

--HG--
extra : transplant_source : %8B%9A%F3%96%8A%0B%FBV%DEn7%CFQ%00%D4%27%0B%BE%CE%C1

ywjrg/pannellum,mpetroff/pannellum,psteph801/psteph801.github.io,mpetroff/pannellum,quentinyang/pannellum,riuson/pannellum,riuson/pannellum,ywjrg/pannellum,eric-seekas/pannellum,Benvii/pannellum,quentinyang/pannellum,Benvii/pannellum,mpetroff/pannellum,riuson/pannellum,psteph801/psteph801.github.io,eric-seekas/pannellum,Benvii/pannellum,psteph801/psteph801.github.io,ywjrg/pannellum,riuson/pannellum,ywjrg/pannellum,eric-seekas/pannellum,eric-seekas/pannellum,quentinyang/pannellum,psteph801/psteph801.github.io,Benvii/pannellum,quentinyang/pannellum,mpetroff/pannellum