First, there is no "Search" button--searches will begin automatically as you fill in the gtk dialogue. Note there are minimum string length requirements. For instance the Town search only "activates" after 3 characters are typed, to prevent a huge number of results (which would take a lot of CPU time to find and display). If you really need to search for two character towns, you'll have to modify the navit source code.
tfw спать ещё неохота, бошка уже не варит, дрочить лень. Такой вечер.