WPF - Dragging multiple gridrows not working

[TomQv]

• Selecting multiple rows in a grid.
• trying to start a drag-operation with left mouse button down on the selection
• selection is cleared immediately, and dragging is initiated with just that single row where the mousedown was clicked.

Only WPF, on OSX this is working fine with multiple rows

Reproducible with Eto.Test "Drag and Drop"

[TomQv]

The following hack added as a style is a workaround, if someone needs this:

Eto.Style.Add<Eto.Wpf.Forms.Controls.GridViewHandler>(null, handler =>
{
	Point p0= default (Point);
	object row = null;

	var swcgrid = (handler.Control as System.Windows.Controls.DataGrid);
	//swcgrid.AlternatingRowBackground = AlternateRowsColor;

	swcgrid.PreviewMouseDown += (object sender, System.Windows.Input.MouseButtonEventArgs e) =>
	{
	// avoid clearing the selection of multiple items, when starting to drag selected items
	// https://stackoverflow.com/questions/16894348/datagridview-multirow-select-clearing-on-left-mouse-button-drag-and-drop
		
	   row = null;
	   if (e.LeftButton == System.Windows.Input.MouseButtonState.Pressed &&
			swcgrid.SelectedItems.Count > 1)
		{
			//find item under mouse
			var p = e.GetPosition(swcgrid);
			row = handler.GetCellAt(new Eto.Drawing.PointF((float)p.X, (float)p.Y), out int c, out int r);
			if (swcgrid.SelectedItems.Contains(row))
			{
				swcgrid.Focus();
				p0 = e.GetPosition(swcgrid);
				// it is selected, so dont proceed with this event, otherwise WPF would deselect all, whoch would make dragging impossible
				e.Handled = true;
			}
		}
		else if (e.RightButton == System.Windows.Input.MouseButtonState.Pressed)
		{
			// make sure, grid gets focus on right mouse click, important for Popup-menu
			swcgrid.Focus();
		}
	};

	swcgrid.PreviewMouseUp += (object sender, System.Windows.Input.MouseButtonEventArgs e) =>
	{
		if (row != null)
		{
			// check if mouse up was at the same point like mousedown, meaning, there was no dragging
			var p1 = e.GetPosition(swcgrid);
			if (p0 == p1)
			{
				// clear selection and select the row we just clicked
				swcgrid.SelectedItem = row;
				e.Handled = true;
			}
		}
	};
});

[cwensley]

Hey @TomQv, thanks for reporting the issue (and supplying a workaround, it is very helpful!).

[cwensley]

Now fixed with #1505 and #1508

Thanks again for reporting this issue!