This should be fixed in the latest build.

I can confirm that this happens on the unskinned version. Added as: http://www.ventismedia.com/mantis/view.php?id=7454

Seems to be an issue only with the unskinned version.

I just tried it in MM3, then immediately after in MM4 - the behavior is exactly the same.

Here it works. Both MM3 and MM4 have always seemed weird about cursor positioning to me. For example here it seems to do partial selects when jumping to the next field that is longer.

When seqentially editing several tracks in the properties window the last edited field used to be remembered:
The cursor used to be already active in it, -even at the correct position (end/beginning) if I recall that correctly-, when moving forward to the next track (ALT+->)
That useful feature seems lost at the moment.
[Edit]: Affects only the unskinned version