Last week there was a discussion on X (former Twitter) about the usage of the NumberBox in WinUI apps. Should it accept letter inputs or not. The 'conlusion' was that it should because you can enter formulas. But there are also a few developers which don't like this. So I took up the challenge to find a solution for this problem. My first guess was that I should create an AttachedProperty or Behavior for this. I was wrong. AttachedProperties can't be used for this. You can't use them for handing events on controls. Behaviors can but they require you to add an extra NuGet package to the project. Something you might not want. So I decided to use compiled binding (x:Bind) to events, also known as Event Binding.
You can customize the appearance of your apps in many ways by using the XAML framework like WPF, UWP, WinUI and MAUI. Styles let you set control properties and reuse those settings for a consistent appearance across multiple controls. Styling is to XAML what CSS is to HTML. Using styles, you can group a set of properties and assign them to specific controls or all controls of a specific type, and just like in CSS, a style can inherit (BasedOn) from another style.
Starting with WinUI 2.6 there are new styles for most of the controls. It is encourage you to use the new styles, as they better match the design direction of Windows. You can read more about styling.
Accelerator keys (or keyboard accelerators) are keyboard shortcuts that improve the usability and accessibility of your Windows applications by providing an intuitive way for users to invoke common actions or commands without navigating the app UI. You can add them to a Button using the KeyboardAccelerators property. See the example below.
In the XAML of WinUI3 apps you can use the inline syntax for creating Rows and Columns inside a Grid. This is a feature which Avalonia had for a long time. It is more compact and works fine as long as you don't need a Max or Min Width/Height.
The following screenshot shows you a Grid with 2 Rows and Columns. Both in equal size. Using 4 Rectangle elements I created the Microsoft logo inside this Grid.
The following screenshot shows you the same Grid but now with inline RowDefinitions and ColumnDefinitions. It saves you a few lines of XAML.
