Hi Stoyo,
We have a problem with the repaint of grid lines when moving nodes programmatically (using .Move method), namely that the grid lines are not always drawn when a node is moved.
To illustrate this issue I placed a diagram view on a form and I added the following code:

[code]
public partial class Form1 : Form
{
ShapeNode node;

public Form1()
{
InitializeComponent();

diagramView1.MouseMove += new MouseEventHandler(diagramView1_MouseMove);

diagram1.BackBrush = new MindFusion.Drawing.SolidBrush("#FFFFFFFF");
diagram1.MeasureUnit = GraphicsUnit.Millimeter;
diagram1.GridSizeX = 1;
diagram1.GridSizeY = 1;
diagram1.GridStyle = GridStyle.Lines;
diagram1.ShowGrid = true;

node = new ShapeNode(this.diagram1);
node.Shape = Shapes.Rectangle;
this.diagram1.Nodes.Add(node);

}

private void diagramView1_MouseMove(object sender, MouseEventArgs e)
{
PointF mousePosition = diagramView1.ClientToDoc(e.Location);
node.Move(mousePosition.X - node.Bounds.Width / 2, mousePosition.Y - node.Bounds.Height / 2);
}

}

[/code]
The issue is visible when the mouse is moved slowly over the diagram.
We tried to use the Invalidate method of diagram/diagramView; it works ok, but it leads to bad performance when many items are drawn on the diagram.

How can we solve this issue (we are using version 5.3.5)?

Regards,
Cornel

Another approach you could try is to use the StartInteraction method from this version to implement that movement mode:

https://mindfusion.eu/_beta/fcnet54_startintr.zip

diagramView.StartInteraction(
	new InteractionState(node, 8, Action.Modify), node.GetCenter()); 

This simulates interaction started by the user, and while it is in progress, the control draws everything except the moved node by copying the content of a cache bitmap to the screen. The cache also includes the full grid, so the lines appear as expected.