WPF中基于动态百分比的宽度

maybe you guys can help me figure this out: I have a Dictionary and an ItemsControl that is binded to that dictionary. The Key of each entry determines the content of each Item in the ItemsControl and the Value determines the width of each Item. The big problem with this: The width is a percentage value, so it tells me that, for example, my Item needs to be 20% of its parent in size. maybe you guys can help me figure this out: I h