I've noticed that a few times on windows 8 32 bit, photoshop cs6 32 bit with 4gb of ram, a nVidia 8400 gs graphics card and open gl seems to work fine.
I guess that's probably some kind of glitch.
One way to get back the dropdown is to click on the Curves Display Options in the flyout menu and then just click OK in the dialog.
Added: It doesn't seem to happen if the crop tool is set to Classic Mode.
Message was edited by: R_Kelly
I have escalated this issue and hopefully this will be fixed in the near furture.
in the meanwhile as Kelly has mentioned, this is the workaround, everytime you use crop you have to click the cusrve display option.
This is not the permament solution to the problem though .
Thanks all for your patience.
Thank you!!! I have been probing around for hours to solve this issue and came across this thread. I hope there will be a permanent fix soon.......
This problem still persists. I have just upgraded today to CS6 with Adobe Cloud so I have the latest release (13.0). I am editing in LAB, and lightness, a, and b in a curve adjustment layer are often inaccessible. I cannot change the properties of the curve or select a preset. The dialog will move and close and it will allow me to change points on the lightness channel (displayed as default). The problem doesn't seem to have anything to do with the crop tool; it seems to happen randomly, and it happens too often!
Thank goodness R_Kelly proposed a "fix." But I agree, this is so fundamental that it should be resolved.
[I am running under Windows 7 with a new Dell PC using an i5 processor and the default Intel 2500 grapics.]
Update photoshop cs6 to version 13.01 and that should correct the problem.
In photoshop go to Help>Updates to download an install the latest updates for your adobe programs.