Tell me more ×  i've got two comboboxes with the same content.
the user should not be allowed to choose the same item twice.
therefore the comboboxes' contents (= selectedindex?) should
never be equal.  my first attempt was to comapare the
selectedindex with a datatrigger to show/hide a button:
<DataTrigger Binding="{Binding ElementName=comboBox1,
Path=SelectedIndex}" Value="{Binding ElementName=comboBox2,
Path=SelectedIndex}">  it seems that it is not possible to use
Value={Binding}. is there any other way (if possible without
using a converter)? thanks in advance!  share|improve this
question add comment  2 Answers  Option 1  You could use
ValidationRules -- it can also be done in XAML, and will work
for a one-off situation. It would be extremely localized and not
something I would recommend since the rule would not be
reusable. Maybe somebody else can come up with a generic rule to
encompass different inputs. Try this out.          <Binding
Path="Whatever" UpdateSourceTrigger="PropertyChanged">