Adjusting dropdown in ExtJS combobox

I need such combobox, that's it dropdown's width ant that one of开发者_JS百科 input are different and dropdown is adjusted to the right edge of the input.

First part is easy - juts set matchFieldWidth to false and assign listConfig.width = something. But what is the easiest way to perform the adjustment? Here is a picture which illustrates the question.

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I'll be the first, but will not gain a reputation - all we should do - is just set pickerAlign to tr-br.