Single Top Menu Bar for all applications

I know it's  a bit old, but I come from the OS X world myself, thought I'd share my findings. Try Arch Linux + Xfce4 + topmenu-gtk + Plank + some additional config (have to figure out yourself, sry) + functinal keys remapping for a much closer resemblance of OS X behaviour.

For the lonely stranger who's tired of pressing that pesky Ctrl function key with their pinky I suggest remapping Alt to Ctrl and Ctrl to Alt, which would give a significantly more pleasant OS X-like experience of pressing keyboard shortcuts with a thumb. Observe, my .Xmodmap file:

!----------------------------------------------------------

! Swap Control and Alt keys, both sides

!----------------------------------------------------------

! First clear all modifiers & control

clear control

clear mod1

clear mod4

! Swap Control_L and Alt_L

keycode 64 = Control_L

keycode 37 = Alt_L Meta_L

! Menu becomes Alt_R Meta_R (AltGr)

keycode 135 = Alt_R Meta_R

! Define Control_R and Alt_R similar to Control_L and Alt_L

keycode 108 = Control_L

keycode 105 = Alt_L Meta_L

! We need to set keycodes first, as some programs (emacs!) read

! the key names and seem to ignore what's below.

add mod1    = Alt_L Alt_R Meta_L Meta_R

add mod4    = Super_L Super_R

add control = Control_L Control_R

Additionally, you would have to play around with Xfwm and Xfce keyboard shortcuts to make them feel more OS X like, according to the Ctrl Alt switch. Also, if you use Firefox, there's an add on called "Key config", which would help remapping the usual browser Ctrl+Tab tabswitcher to Alt+Tab, which would give you a proper OS X experience within a browser as well. You'd understand what I mean by all of that if you use OS X's shortcuts heavily.