wpf histogram fidelity degrades when resized smaller - wpf

Question

I've developed a simple Histogram control that shows the distribution of grayscale colors (1 to 256 bins) in a live image. The control renders rectangles in an ItemsControl whose ItemsContainer is a ViewBox. Everything is working fine for the most part, however when I resize the grid column (using a GridSplitter) that is hosting the control the fidelity of my histogram begins to degrade.
Here's a couple shots of the histogram at its initial state, and then when it has been resized horizontally (notice the dark vertical lines in the forest of green rectangles...it gets worse the smaller I go):
Here's the XAML that renders the histogram:
<ItemsControl x:Name="_Histogram" Margin="1,3"
ItemsSource="{Binding HistogramCollection}"
VerticalAlignment="Bottom">
<ItemsControl.Template>
<ControlTemplate TargetType="ItemsControl">
<Grid>
<Viewbox Stretch="Fill" MaxHeight="100" >
<ItemsPresenter />
</Viewbox>
</Grid>
</ControlTemplate>
</ItemsControl.Template>
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal" />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<Grid>
<Rectangle Fill="LimeGreen"
Stretch="Fill"
Height="{Binding Bin}"
MinWidth="1"
StrokeThickness="0"
VerticalAlignment="Bottom"
HorizontalAlignment="Stretch"
RenderOptions.EdgeMode="Aliased"
UseLayoutRounding="True"
MouseEnter="Rectangle_MouseEnter"
MouseLeave="Rectangle_MouseLeave"
/>
</Grid>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
Any thoughts? My guess is that WPF is throwing out some Visuals in order to evenly distribute the rest.
I've experimented with using a Polygon in lieu of ItemsControl and Rectangles to distribute my bin points and the behavior goes away, however, I need the ability to MouseOver the histogram and show a popup (among other things, e.g. select a range of bins and update properties in my ViewModel). If you know of a way, using the Polygon approach, that I can hover in the green area and determine that I'm over a specific bin I'm definitely open to that.
UPDATE:
Removing RenderOptions.EdgeMode="Aliased" on the Rectangle XAML seems to solve the problem of black line glitches. Though it does render somewhat pale in the Designer (using d:DesignData), but it seems to render fine at runtime. I'm going to hold off on marking as "Answered" until others have had a chance to chime in. I'm really interested in the polygon approach because I get a crisper histogram when resizing to a larger width (the wider I make the histogram, the more pixelated the peaks get, i.e. the peaks are flat because of the width of the rectangle, which presents as a jagged plot instead of smooth curved plot). If only Point had a mouse over handler :D.