AFTER EFFECTS _ tips

 To launch a second instance of After effects :
"C:\Program Files\Adobe\Adobe After Effects CC 2015.3\Support Files\AfterFX.exe" -m
type it in cmd (windows) or save it in a .bat file and double click.


Shortcuts
b / n  work area end / start
- / =   zoom in/out timeline
ctrl shift h  Toggle Layer Controls in viewport
shift F4  toggle parent column
F4   toggle column
ctrl a   select all
ctrl shift a / F2  deselect all
ctrl L  lock layer
ctrl shift t   open effect panel for selected layer
ctrl shift p   open dialog box for position of selected layer
ctrl+   increase scale selected layer
ctrl-  decrease scale selected layer
shift F3  toggle graph editor/layer mode
ctrl shift d   split layer according time position
shift + / shift -   change blending mode
[    in point(start) of the layer
]  out point (end) of the layer
Alt Ctrl Shift N Split the frame containing the active viewer and create a new  locked viewer
x focus selected layer
Ctrl+Alt+B Set work area to duration of selected layers 
Shift+Esc Toggle between two recent composition
 Ctrl+Alt+U To choose which layer controls to show in a view, shortcut for :  choose View > View Options
Alt+Shift+M Set key on mask path for selected layer
L Toggle waveform on timeline

To manually edit/add shortcuts, edit the .txt file located here:
C:\Users\UserName\AppData\Roaming\Adobe\After Effects\*.*\Adobe After Effects *.* Shortcuts.txt
- "ToggleTabPanelMaximize" = "(RParen)"
-  "TimeTrimIn" = "(Ctrl+Alt+Shift+I)"
- "TimeTrimOut" = "(Ctrl+Alt+Shift+O)"
- for azerty keyboard, add "Pad" before numbers ex : 1 -> Pad1

Easy crop comp : select region of interest then composition - crop comp to region of interest
Preserve underlying transparency (small T check) = clipping mask in Photoshop
ctrl + double click pan behind tool = pivot to center

Some expressions

loopOut(type = "continue");
loopOut(type = "cycle", numKeyframes = 2)
loopOut(type = "pingpong", numKeyframes = 2)
loopOut(type = "offset", numKeyframes = 2)

# force fps animation
posterizeTime(8);
value

# round value
Math.round(effect("Slider Control")("Slider")) 
# keep only one decimal
effect("Slider Control")("Slider").value.toFixed(1)

#copy animation from layer and offset time
thisComp.layer(1).position.valueAtTime(time-1)