When adding a new statement on Wikidata, the automatic change of focus from the property to the value can cause several problems.

Automatic selection of the wrong property
In the case where two property start with the same word, the shorter is automatically selected when it appears first in the list.
Example (tested on Q25356 with interface in French)

• I want the property "pays d'origine"
• I start typing "pays"
• the property "pays" is automatically selected and the focus moved to the value

When the property "pays" is not the first one in the suggestion lists, for example on the sandbox item, this doesn't happen.

Superposition of the two menus
In the example above, the focus is moved to value, but the suggestion menu of the property field is still opened, in the same time as the suggestion menu of the value field: both are superposed and the new menu is under the property one, therefore selcting a value is difficult.