Got a Hammer Editor bug here.

[Carnicide]

So, I compile my map like usual and I run alien swarm from steam because the run game after compile is buggered.
I close the game after I'm done looking and bam all 4 of the windows on the editors are locked I can still move things around in the windows but I cant see a damned thing.
I found out that if I minimize hammer while I'm testing out the map it keeps that from happening.
I just thought id let everyone know that this is what I've experienced.

[HydratedPinkus]

Yeah this happens to me too, same solution works.

Its really weird, because on very rare times it actually still works after playing alien swarm.

[Criminal_Colt]

Same here mate, thanks for the work around.

Wasn't going to post because it's been years since I've used hammer and thought it probably wasn't specific to swarm...seems it is. :)

[D1sgaea1]

nice one, thanks!

[Johnnsen]

A better workaround is -windowed in additional game parameters when compiling.

[Beezy]

Same here mate, thanks for the work around.

Wasn't going to post because it's been years since I've used hammer and thought it probably wasn't specific to swarm...seems it is. :)

Naw I've had that problem with L4D Authoring Tools too.

Minimizing never works for me though. Neither does closing the vmf and reopening it.

I always have to close Hammer entirely. :(

A better workaround would be -windowed in additional game parameters when compiling.

I have it set to not run the game when it's done compiling, and my game is set to windowed.

Still happens.

[Nephian]

I am also having this issue (visually frozen window drawspace in Hammer after running Alien Swarm). It's adding a lot of extra time and frustration to the creation process.

Valve fix would be muy bueno.

[jamble7k]

I found if I run AS in window mode this doesn't happen to me, fullscreen though - it breaks all the Hammer view ports.