I've been testing internal scripting in a differnt way, to see if it worked:
say(-x)
internal x times
I found a glitch, I'll tell details later.
You have piqued my interest... How far away is later?
Sorry, I've been busy. But it's almost what avengah said:
It only detects one internal command, but you see an empty text box as well.
Here's what I did:
I played a level, the last script being executed made

sad and created a grey centered text box saying "Here's your cake" or something similar. I quitted without saving (because I had no way out, including suiciding).
After that, I created a level just for testing internal scripting. I created 3 scripts. One called script1 had this:
say(-1)
alarmon
(empty line)Another called script2 had something like this:
say(-2)
playef(9)
(something I don't remember)
(empty line)The last one, called script3 had someting like this:
say(-4)
flash(5)
gotoposition(1,1)
playef(10)
(empty line)Here's what happened when I triggered script1 (I triggered every script in the editor):

turned sad, a centered grey text box with "Here's your cake" appeared and the alarm turned on.
When I triggered script2:

turned sad, a centered grey text box with "Here's your cake" appeared and a flash sound was played with neither the white screen nor shaking. If script1 was triggered earlier the alarm didn't turn off.
When I triggered script3:

turned sad, a centered grey text box with "Here's your cake" appeared and a flash with neither sound effect nor shaking and normal duration appeared. If script1 was triggered earlier the alarm didn't turn off.
I changed script3 slightly. I also changed script2 slightly but I don't remember how. Here's the new script3:
say(-4)
gotoposition(1,1)
flash(5)
playef(10)
(empty line)Here's what happened when I triggered it:

turned sad, a centered grey text box with "Here's your cake" appeared and

immediately disappeared form the place he/she was and appeared near the top left of the screen. If script1 was triggered earlier the alarm didn't turn off.
Then, I realized this: only the 1st line was executed. The same behavior happened with the new script2, IIRC.
It's likely that the reason to why an empty box appeared when avengah tested it is because avengah tested it immediately after he/she opened VVVVVV.
The fact that you need to play a level before testing to make a text box appear is similar to
a glitch I've reported that isn't related to internal scripting. You need to make a mistake in scripting to reproduce this, though.
The fact that it only executes the 1st line might (or should) have been discovered before by FIQ (since he's the one who discovered the say(-1) glitch to execute int. scripting). Did anyone discover this before?
EDIT: This thread already has 330 replies!
