Fast Scroller works wrongly after customizing CCP Dialog theme.

[Wunengwei]

Hello! I try to change the CCP Dialog size by these [two ways] (https://github.com/hbb20/CountryCodePickerProject/issues/265#issuecomment-458756357), and both of them are available, but they cause a bug too. If the CCP Dialog size is changed and the height is not matching parent, the Fast Scroller will jump to the wrong position when user click or drag the scroller bar and cause the list jump to the wrong place. By the way, if the CCP Dialog have the properties about size will make it better in my opinion.