[WPF - C7] - Problem with datagridview

Question

Hi,
I have a datagrid and when I drag fastly the vertical scroll bar to the bottom it shows like that

If I click on "Install" (it's a datagrid cell with a button inside), it doesn't work and I get that

If now I click on "Install" it works... but it's not what i want!

How can I fix this problem?
I would like the button start immediatly.

Thank you very much

Cheers, Blacksun

Answer 1

Hi, I cannot reproduce your problem without additional information. Try following Demo:

<Window x:Class="WpfApp1.Window34"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp34"
        mc:Ignorable="d"
        Title="Window34" Height="450" Width="800">
  <Window.Resources>
    <local:ViewModel x:Key="vm"/>
  </Window.Resources>
  <Grid DataContext="{StaticResource vm}">
    <DataGrid ItemsSource="{Binding View}" AutoGenerateColumns="False">
      <DataGrid.Columns>
        <DataGridTemplateColumn Header="Button">
          <DataGridTemplateColumn.CellTemplate>
            <DataTemplate>
              <Button Content="{Binding Col1}" 
                      Command="{Binding Cmd, Source={StaticResource vm}}" 
                      CommandParameter="{Binding Col2}"/>
            </DataTemplate>
          </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>
        <DataGridTextColumn Header="Col1" Binding="{Binding Col1}"/>
        <DataGridTextColumn Header="Col2" Binding="{Binding Col2}"/>
      </DataGrid.Columns>
    </DataGrid>
  </Grid>
</Window>

Classes:

using System;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Diagnostics;
using System.Windows;
using System.Windows.Data;
using System.Windows.Input;

namespace WpfApp34
{
  public class ViewModel
  {
    public ViewModel()
    {
      ObservableCollection<Data> col = new ObservableCollection<Data>();
      for (int i = 0; i < 10; i++) col.Add(new Data() { Col1=$"Row {i}", Col2=$"Data {i}"});
      cvs.Source = col;
    }
    public ICollectionView View { get => cvs.View; }
    private CollectionViewSource cvs = new CollectionViewSource();

    public ICommand Cmd { get => new RelayCommand((state) => Debug.WriteLine(state.ToString())); }
  }

  public class Data
  {
    public string Col1 { get; set; }
    public string Col2 { get; set; }

  }

  public class RelayCommand : ICommand
  {
    private readonly Predicate<object> _canExecute;
    private readonly Action<object> _action;
    public RelayCommand(Action<object> action) : this(action, null) { }
    public RelayCommand(Action<object> action, Predicate<object> canExecute) { _action = action; _canExecute = canExecute; }
    public void Execute(object o) => _action(o);
    public bool CanExecute(object o) => _canExecute == null ? true : _canExecute(o);
    public event EventHandler CanExecuteChanged
    {
      add { CommandManager.RequerySuggested += value; }
      remove { CommandManager.RequerySuggested -= value; }
    }
  }
}