When Content Doesn't Fit
Sometimes WPF will not be able to honor your requests because you
have asked the impossible. Example 3-33
creates a StackPanel with a Height of 100, which contains a Button with a Height of 195.
Example 3-33. Asking the impossible
<StackPanelHeight="100"Background="Yellow" Orientation="Horizontal"> <Button>Foo</Button> <Button Height="30">Bar</Button> <ButtonHeight="195">Quux</Button> </StackPanel>
Clearly that last button is too big to fit—it is taller than its containing panel. Figure 3-37 shows how WPF deals with this.

Figure 3-37. Truncation when content is too large
The StackPanel has dealt with
the anomaly by truncating the element that was too large. When
confronted with contradictory hardcoded sizes like these, most panels
take a similar approach, and will crop content where it simply cannot
fit.
There is some variation in the way that panels handle overflow in
situations where sizes are not hardcoded, but there is still too much
content to fit. Example 3-34 puts two copies of
a TextBlock and its content into a
StackPanel and a Grid cell.
Example 3-34. Handling overflow
<Grid Background="Yellow" ShowGridLines="True"> <Grid.RowDefinitions> <RowDefinition /> <RowDefinition /> </Grid.RowDefinitions> <StackPanel Height="100" Orientation="Horizontal"> <TextBlock TextWrapping="Wrap" FontSize="20"> This is some text that is too long to fit. </TextBlock> </StackPanel> ...