Q:

My background stretch changes when i open application

My background image changes when i open application 
I used this: 
<Grid Name ="alo">
        <Grid.Background>
            <ImageBrush ImageSource="D:\Smth\Pics\135.jpg" Stretch="None"/>
        </Grid.Background> 

background before launch
background afterlaunch

A:

The image is shown in its native, unstretched size.
In order to make it fill the Grid while keeping its aspect ratio, set Stretch to UniformToFill:
<ImageBrush ImageSource="D:\Smth\Pics\135.jpg" Stretch="UniformToFill"/>

