You could try putting your tab control inside of a ScrollViewer (with horizontal scrolling enabled). Then set an explicit width for your tab control, such that it won't resize, but the ScrollViewer will resize (because of it's relationship to the Grid parent). This should prevent tabs from wrapping, and at the same time allow you to scroll horizontally when necessary. Something like this:
<Grid x:Name="LayoutRoot" Background="White">
<ScrollViewer HorizontalScrollBarVisibility="auto" VerticalScrollBarVisibility="auto">
<y:TabControl Height="64" VerticalAlignment="Top" Width="750" >
<y:TabItem Header="FirstTab" >
<Grid>
<TextBlock Text="1" Grid.Row="0" Grid.Column="0"/>
</Grid>
</y:TabItem>
<y:TabItem Header="SecondTab">
<Grid>
<TextBlock Text="2"/>
</Grid>
</y:TabItem>
<y:TabItem Header="ThirdTab">
<Grid>
<TextBlock Text="3"/>
</Grid>
</y:TabItem>
<y:TabItem Header="FourthTab">
<Grid>
<TextBlock Text="4"/>
</Grid>
</y:TabItem>
<y:TabItem Header="FifthTab">
<Grid>
<TextBlock Text="5"/>
</Grid>
</y:TabItem>
<y:TabItem Header="SixthTab">
<Grid>
<TextBlock Text="6"/>
</Grid>
</y:TabItem>
<y:TabItem Header="SeventhTab">
<Grid>
<TextBlock Text="7"/>
</Grid>
</y:TabItem>
</y:TabControl>
</ScrollViewer>
</Grid>
Thanks,
John
myOSity Project Website, Blog