description:
can not set overflow to default value "hidden : inherited" after its value changed.

build number:
2.5.2.v20100105-0630

steps to reproduce:
1. new a grid.
2. select one cell and go to property editor-advanced, set overflow to "hidden", try to reset to the default value.

expected result:
can reset to "hidden : inherited".

actual result:
can set to "hidden", not "hidden : inherited".

error log:
n/a
need introduce a new cell editor to reset the properties.
fixed it. 

replace "auto" with an empty string.
"auto", "hidden", "scroll", "visible", and empty string stands for "hidden : inherited".

verified in build (2.5.2.v20100113-0630), closed.