Operating system: Windows 8.1 x64
Graphics card: GeForce GTX 560
Broken: 2.70 2525f9c = official RC2
Broken: 2.70 211f08d win64
Broken: 930765f win64-vc12 (most recent experimental x64 build)
Broken: 2.70 930765f win32
Tested in another computer = yes
System information of the second computer = the same of the one mentioned above (Windows 8.1, GTX 560)
Short description of error
Using the new interface feature "Multi-Number Button Editing" on the Dimensions values of the Transform Properties Panel (shortcut=N) doesn't never change the Y value, and the X value sometimes doesn't change, sometimes changes a lot less than the Z value (the only value that changes normally).
Exact steps for others to reproduce the error
Download 2.70 RC2 or most recent builds from http://builder.blender.org/download/
Select the default cube
Press N to open the Transform Properties Panel
Click and hold the X dimension value, drag the mouse down to select Y and Z, then move the mouse left or right (this is the new Multi-Number Button Editing feature)
Release when the value is different than 2.000
The Y value doens't change at all, while the X value changes a little bit, or sometimes nothing. The Z value changes normally.
Also, apparently the "Lock" button next to the values in the Transform Properties Panel ignores the Multi-Number Button Editing. A suggestion would be that it actually locked the value when using this feature, so that you could lock a middle one, like Y, while changing X and Z simultaneouly.