Star ist relativ Einheit, ähnlich wie in% CSS, aber etwas anders
//will split the grid into two columns with equal width
<ColumnDefinition Width="1*" /> //the same as Width="*"
<ColumnDefinition Width="1*" />
//will split the grid into two columns with ratio 1:2
<ColumnDefinition Width="1*" />
<ColumnDefinition Width="2*" />
//will split the grid into two columns, first 50px (fixed), second the rest of the grid
<ColumnDefinition Width="50" />
<ColumnDefinition Width="*" />
//will split the grid into three columns, first 50px, and the rest of the grid splitted with ratio 2:2, which is the same as 1:1
<ColumnDefinition Width="50" />
<ColumnDefinition Width="2*" />
<ColumnDefinition Width="2*" />