xaml - WPF disable ListBox autosizing in uniform grid -

i have following structure:

<uniformgrid horizontalalignment="stretch"  grid.row="0" verticalalignment="top" columns="6"  dockpanel.dock="right"  >   <stackpanel horizontalalignment="stretch">       <dockpanel background="#ff393939"  >           <label content="{lex:loc site}" foreground="#ffe0e0e0"/>       </dockpanel>       <listbox height="300" itemssource="{binding sites.view}" displaymemberpath="name.actualtranslation">       </listbox>   </stackpanel>... 

these stackpanels in uniformgrid should spreaded on whole mainwindow (or view)... still if there item in listbox has longer string needs more place standard width autofits string , have scroll vertically.

i dont want listview gain width if content has not enough place. have scrollviewer in mainwindow in view placed...

what can uniform grid stays same width mainwindow-...

i've tried give name mainwindow , bind width this: width="{binding elementname=mainwindow, path=actualwdith}" ..

though error:

cannot find source binding reference 'elementname=mainwindow'. bindingexpression:path=actualwdith; dataitem=null;

what can fix issue? if need more information or error description isnt clear dont hesitate ask.

update: how should be:

behavior when text long: , scrollbar appears on bottom..

if trying access wpf object name needs have x:key="name" wasn't shown in code above, i.e.

<window x:name="mainwindow" .... 

alternatively can walk tree until find object of correct type,

width="{binding relativesource={relativesource findancestor, ancestortype={x:type mainwindow}, path=actualwidth}"