Hat Blocks

When Green Flag Clicked

onflag {
    # code
}

When Key Pressed

onkey "enter" {
   # code 
}

When This Sprite Clicked

onclick {
    # code
}

When Backdrop Switches To

onbackdrop "backdrop" {
    # code
}

When Loudness >

onloudness > 100 {
    # code
}

When Timer >

ontimer > 100 {
    # code
}

When I Start As A Clone

onclone {
    # code
}

When I Receive Message

on "message name" {
    # code
}

Source