PropertyChanged | lightweight property changed/binding framework | iOS library

You are facing the issue because of binding for DataGridTextColumn.Width doesn't work.

The cause for it is that DataGridTextColumn.Width is of type DataGridLength, TextBlock.Width in it's turn is of type double and the binding does work here.

So as you increase the width of TextBlock, the width of column been increased automatically, but the column's width does not shrink on change of TextBlock.Width.

What you can do is to change return value of multyvalueconverter:

Your main blocker for reusing the style are the bindings to concrete properties and the hard-coded Error string. You need to pass them from outside of the style and control template.

Your comparison of the DataTrigger can be encapsulated in a value converter that returns a boolean for the comparison of any bound property (PosError) with a fixed value (Error) passed as parameter.

The internal elements must bind to the control's properties either by Binding.ElementName, where the the named UserControl is the binding source or by using Binding.RelativeSource.

HeaderAndTextBox.xaml

First of all, you are refering to the wrong documentation, yours is for UWP, not WPF.

• UWP UniformGrid
• WPF UniformGrid

The behavior should be the same, but it is not explicitly stated in the referenced documentation for WPF. However, there seems to be an issue that stems from setting VerticalAlignment to Center and is not related to the ItemsControl, it will be the same for an isolated UniformGrid.

Whenever the UniformGrid contains more than the maximum number of items it can display (Rows x Columns) and the VerticalAlignment is set to any other value than the default Stretch, all of the items are displayed regardless of the number of rows, but respecting the number of columns.

What you could do is remove the VerticalAlignment and try to compensate for it by aligning the ItemsControl in a way that it fits your original intent.

There are some issues with your code, but I will focus on the main:

Your binding source is wrong. From that the binding source it will start with the property path. To resolve the property DisplayNumFilter the source has to be set to this.

This is a task that cries out for a Custom control and Visual States instead of a UserControl with Triggers. But if you must do this as a UserControl (and I don't blame you because that's a lot to learn at this stage) then here goes:

First of all, when you use ElementName it is supposed to refer to elements that the XAML processor has already seen, previously in the current UI being laid out. Not elements inside the control being styled. I don't see that approach working.

If you want the TextBox and TextBlock inside a TextBoxWithPlaceholder to use the properties of that outer control, you could bind them to it, inside your control's XAML. For example, to rewrite a small part of that binding the background.

I propose the behavior bellow:

• When a cell is clicked on the selected row, the behavior of the DataGrid is unchanged.
• When a cell is clicked on a not select row, its row is selected and the cell in the AutoEditColumn is set in edition mode.
• When the DataGrid gain focus from keyboard (tab navigation), the cell in the AutoEditColumn and selected row is set in edition mode.

To achieve this, one can listen on the CurrentCellChanged event.
Here a helper class that implement the described behavior :

*System.ArgumentException: 'The ItemsSource elements do not contain a property [name of property relevant to this column]. Ensure that the binding path has been set correctly.' *

I could reproduce your problem, it looks binding context error cause this problem, please feel free report this problem in community tool kit github. And currently we have a workaround that use string list to replace item list like official processing. And the other way is set binding EnumDisplay property same as DataGrid item one property.

For example, if your DataGrid item model contains a property called Description, you need set same property name for EnumDisplay. It will solve the above exception, but the default DataGridComboBoxColumn cell content will be null.

There is some confusion I think about the different classes:

• Xamarin.Forms.BindableObject is meant to be used to create something like a custom view with bindable properties. It also implements INotifyPropertyChanged, but I don't think you should use it for a ViewModel.

• The ObservableObject from the community toolkit can be used as a base class for any class you like to use with data binding, you don't need to implement it yourself.

• If you have some custom requirements for handling the OnPropertyChanged, you do need to implement the interface yourself, but if you just want to have default behaviour, ObservableObject is perfectly fine.