Make sure "Barrel on collision with Ground"

is the first condition in the event

so it goes

+Barrel on collision with Ground

and

+Barrel.physics.velocityY > A

     -> explode!

If that doesn't work, add "For each Barrel" at the top, and have the above as a sub event.

Using another object with the blend mode set to "destination out" might be of use.

It'll make it transparent, but also make the object underneath transparent where it overlaps.

Check out the "compositing" section

Increase density / decrease elasticity / increase linear damping

also i'm not sure exactly what type of game you're making but it looks like it could use walls on either side

If your "trigger once" is below the "for each element", try placing it above.

yep, don't be afraid of assigning UID's, it's actually quite simple once you've done it a few times.

First you'll need to give enemy01_box an instance variable which will contain the UID of the actual character sprite. I'll call the variable "CharUID"

underneath "pin to..", add another action:

-> enemy01_box set value CharUID to enemy_01.UID

and then after this, in order to pick the correct character sprite for the box, add the following underneath the "For each.. " condition:

+ enemy_01 pick instance with UID: enemy01_box.CharUID

*edit: I accidentally typed "enemy_01.uid pick" instead of "enemy_01 pick"

Nope.

You can, however, instead of an imagepoint, store a position using instance variables.

if you give the sprite two extra instance variables and name them, for example: "pointX" and "pointY"

+everytick

     -> set sprite.pointX to sprite.X + cos(B)*C

     -> set sprite.pointY to sprite.Y + sin(B)*C

Where B is the desired angle of the point from the origin, and C is the desired distance of the point from the origin.

It's likely you'll get a problem solving response if you post the .capx..

without it, it's hard to tell what is going wrong.

Though it's never been a problem for me, I agree that this should be a feature. it should be ctrl +drag edge

Nope, but a bit of maths won't do you any harm :p

If you keep sizes to powers of 2 (2,4,8,16,32,64,128.. etc) then it makes everything easier to position and size though.

Change the size manually in the object properties.

Also if you had snapping on, you could easily move it back to it's right spot.