I found the solution.
Static resource have to be declared at App.xaml:
<Application.Resources> <Style x:Key="myStyle" ...>...</style></Application.Resources>
Question
Is there the way to declare static resource once(for example style for some control), and to use that resource in any XAML in the application? I want to avoid coping same resource again on every new page or user control.
Solution
I found the solution.
Static resource have to be declared at App.xaml:
<Application.Resources> <Style x:Key="myStyle" ...>...</style></Application.Resources>