Created attachment 140913 [details]
Result when entering "0.25" and ".25" in the animation duration text box (upper and lower images, respectively)

I've been using Impress heavily for the first time and I came across something that is a bug, if only because it creates a counter-intuitive UI behavior.

For example, suppose I create an object on a slide, open the animation panel at right, add an animation, and switch it to  Entrance:Fly In.

I then decide I want to change the duration from 0.50 sec to 0.25 sec.  If I highlight the entire text in the text box, and directly enter "0.25", the result is 0.26.  (Upper image, below)

If I omit the zero and simply type ".25", "2.52" gets entered instead, forcing the decimal point to the right and retaining part of the previous number. (Lower image, below)

The third issue is that the text field can't be cleared, which, I presume is either because of data format validation or validating the typed value against the list of values in the dropdown.  

Regardless, it's clear to me that the text box is validating the data as the user is keying in the values which results in unexpected behaviors when the user is focused on entering a number.  All data validation should be postponed until after the control loses focus.  

I'll happily file it as a bug, but thought I'd post here first in case this is something that has been discussed and decided is expected or desired behavior.