Which hotkeys?
https://powdertoy.co.uk/Wiki.html?id=hotkeys
Caps Lock- Specific Element Erase
Insert- Replace mode
TAB- Circle/Square Brush
Space- Pause
Q- Quit
Esc- Quit
Z- Zoom
S- Save stamp (+ Ctrl when STK2 is out)
L- Load last saved stamp
K- Stamp library
C- Cycle view mode
1-9- Set view mode
P- Save screenshot to .ppm
F- Pause and go to next frame
G- Grid
H- Show/Hide HUD
D- Debug mode (+ Shift when STK2 is out)
I- Invert Pressure and Velocity map
T- Vine mode
W- Toggle gravity modes (+ Ctrl when STK2 is out)
R- Reset LIFE generation (when in Debug mode)
~- Python Console
=- Reset pressure and velocity map
[- Decrase brush size
]- Increase brush size
B- Decoration Mode
Ctrl+C/V/X- Copy/Paste/Cut
Ctrl+Z- Undo
Ctrl+Cursor drag- Rectangle
Shift+Cursor drag- Line
MMB / Alt+LMB- click Sample element
Mouse scroll- Change brush size
Ctrl + Mouse scroll- Change vertical brush size
Shift + Mouse scroll- Change horizontal brush size
Shift + Ctrl + R- Horizontal mirror for stamp (need stamp preview up)
Ctrl + R- Rotate stamp counterclockwise (need stamp preview up)
Ctrl + Arrow keys- Shift stamp in the direction of arrow key one pixel (no walls)
Shift + L alternative button + L control button- Select subject for Specific Element erase
Ctrl + = - Reset Electricity
Ctrl + Shift + LMB/RMB- Fill