#260 scrollbar and MouseWheel

[Mats Bengtsson]

The scrollbar should bind to MousWheel on non aqua platforms too:
if {[tk windowingsystem] eq "aqua"} {
bind Scrollbar <MouseWheel> {
tk::ScrollByUnits %W v [expr {- (%D)}]
}
bind Scrollbar <Option-MouseWheel> {
tk::ScrollByUnits %W v [expr {-10 * (%D)}]
}
bind Scrollbar <Shift-MouseWheel> {
tk::ScrollByUnits %W h [expr {- (%D)}]
}
bind Scrollbar <Shift-Option-MouseWheel> {
tk::ScrollByUnits %W h [expr {-10 * (%D)}]
}
}

but the bindings look a bit different, see MouseWheel in library/text.tcl