Expressions doesn't work in object variable editor as value.

When I try to use expressions as value in object variable editor such as
object.Variable(A) = object.Variable(B) - X, it doesn’t work for whatever reason but I guess it should work, as if I do the same using an event, it works.

It’s not a bug, you can only enter value but not expression inside the variables’ editors.

You gonna tell me why ? Because how do you evaluate an expression like “TimeElapsed()” when the game is not running ?