What does F4 do?

[Incredible Canemian]

Most of the F keys do what they say in the controls tab, but for some reason F4, which isn't paired to anything in the controls tab, makes a sort of cannon noise every time I press it. Does this actually do anything?

[Terin]

Apparently it refreshes the textures, used back when the game engine had a tougher time dealing with texture memory in OpenGL. I don't think that's really been needed for a while, though.