[votan]

This is how I do it in Potion Maker:

    <Tooltip name="PotionMakerTooltip" inherits="ZO_ItemIconTooltip" mouseEnabled="true" movable="true" hidden="true">
      <ResizeToFitPadding width="48" height="57"/>
      <DimensionConstraints minX="416" maxX="416" />
    </Tooltip>

No issue with the size.