How can I get the size of a WPF panel that was changed during runtime?

Question

I have a panel that's width can be resized during runtime

    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="770*"/>
        </Grid.ColumnDefinitions>
        <panels:NavigationPanel x:Name="cmBar" Margin="2,2,0,2" HorizontalAlignment="Left" Width="220"/>
        <panels:DetailAreaPanel x:Name="detailGrid" Margin="224,2,2,2" />
    </Grid>

When the program is closed i want to save the new width in the registry. So the program will load to the same size next time its opened. I have everything working except the width, unless i hardcode the new width. So i would assume that my save is wrong.

all[5] = cmBar.ActualWidth.ToString();

all[] is then wrote into the registry. No matter how the panel is resized cmBar.ActualWidth is always 220. Any ideas?

Answer 1

The little piece that says Width="220" sets the width to 220, and that will not change unless explicitly changed from the code-behind. Are you changing the panel's width in code-behind? If not - then its width really doesn't change, and stays at 220 throughout its lifetime.

Answer 2

HorizontalAlignment="Stretch" will allow the control to size to its parent. "Left" just sizes to itself and leaves empty space to its right.

Answer 3

Aviad P. had one this right the .Width is what is causing the problem. The solution is is when i load the width to load it as .MaxWidth This will do the resizing but allow .ActualWidth to have the real width of the panel.