Treeview horz scroll by trackpad on Mac

Original Reporter info from Mantis: Alextp

• Reporter name: CudaText man

Description:

This is small diff which uses ssHyper shift state to adapt to horz scroll on Mac.
W/o it Tree cannot scroll horz by trackpad.
Tested on real Mac.

ps. Listview don't need this patch, it works already.

Mantis conversion info:

• Mantis ID: 31897
• Version: 1.9 (SVN)
• Fixed in revision: 55264 (#7b1d5cda)