When you type a few letters in BarahaPad OR BarahaIME, auto-completion box displays matching words from the word dictionary. You may add frequently used long words to the word dictionary, which will be shown in the auto-completion box.
Navigate through the list using arrow keys to select the required word and press TAB or ENTER key. You may press ESC to cancel the suggestions.
You can enable/disable auto completion feature in BarahaIME and BarahaPad settings.