ID:2196252
 
Resolved
Macros behaved badly when command_text was set to ".alt" for old-style macro support. Specifically, they would treat macros as repeatable that were not, and they would stack their commands without limits.
BYOND Version:510
Operating System:Windows 7 Pro
Web Browser:Firefox 50.0
Applies to:Dream Seeker
Status: Resolved (511.1367)

This issue has been resolved.
if you hold down a macro key it will continue repeating even after releasing the key it use to just stop when you released it but now it seems to continue onwards for a long time dependant on how long you held it down
Are you using command_text = ".alt"?
The .alt thing is next on my list to look at.
ya i am using the command_text=".alt" its weird because in the past it would always stop but due to some update with byond at some point it now doesn't. Like other day i held the macro down for 5 minutes after releasing it went on for i think another 5 minutes and only way to break it is to relog
Alright, so a quick explanation of what's going on here:

Basically, command_text .alt is treating all macros as +REP macros. Not only that, but it calls the command once for each macro in the current macro list plus as additional one.

BYOND by default queues up macros that haven't been able to be processed for later ticks. Any verb that isn't set to instant will enter the queue. The queue is processed over time. That's what causes the commands to hang around for 2 to 3 times as long as you held down the key.
Lummox JR resolved issue with message:
Macros behaved badly when command_text was set to ".alt" for old-style macro support. Specifically, they would treat macros as repeatable that were not, and they would stack their commands without limits.