Bypass read only cells in DataGridView when pressing TAB key

private void dataGridView1_CellEnter(object sender, DataGridViewCellEventArgs e)
{
   if (dataGridView1.CurrentRow.Cells[e.ColumnIndex].ReadOnly)
    {
        SendKeys.Send("{tab}");
    }
}

Overriding the SelectionChanged event is the right approach. The property CurrentCell can be used to set the current cell. You want something like this:

private void dataGridView_SelectionChanged(object sender, EventArgs e)
{
    DataGridViewCell currentCell = dataGridView.CurrentCell;
    if (currentCell != null)
    {
        int nextRow = currentCell.RowIndex;
        int nextCol = currentCell.ColumnIndex + 1;
        if (nextCol == dataGridView.ColumnCount)
        {
            nextCol = 0;
            nextRow++;
        }
        if (nextRow == dataGridView.RowCount)
        {
            nextRow = 0;
        }
        DataGridViewCell nextCell = dataGridView.Rows[nextRow].Cells[nextCol];
        if (nextCell != null && nextCell.Visible)
        {
            dataGridView.CurrentCell = nextCell;
        }
    }
}

You'll need to add a test for the current cell being read only and loop while the next cell is invisible or read only. You'll also need to check to make sure that you don't loop for ever if all cells are read only.

You'll have to cope with the case where the display index is different to the base index too.

To get this behaviour just when pressing Tab you'll need to add a KeyDown handler:

private void AlbumChecker_KeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyCode == Keys.Tab)
    {
        SelectNextEditableCell(DataGridView dataGridView);
    }
}

and put the first code in this new method.

You might want to check that the DataGridView has focus too.

I did an example inheriting DataGridView class. The example works for TAB and ENTER keys so the user can quickly insert data, but can still use the mouse or the up, down, right, left keys to select the cells and copy them to an excel. It works simulating several TABs until the Grid gets to a non ReadOnly Cell. Hope it’s useful.

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;

namespace System.Windows.Forms
{
  class MyDataGridView : DataGridView
  {
    protected override bool ProcessDialogKey(Keys keyData)
    {
      if (keyData == Keys.Enter || keyData == Keys.Tab)
      {
        MyProcessTabKey(Keys.Tab);
        return true;
      }
      return base.ProcessDialogKey(keyData);
    }

    protected override bool ProcessDataGridViewKey(KeyEventArgs e)
    {
      if (e.KeyCode == Keys.Enter || e.KeyCode == Keys.Tab)
      {
        MyProcessTabKey(Keys.Tab);
        return true;
      }
      return base.ProcessDataGridViewKey(e);
    }

    protected bool MyProcessTabKey(Keys keyData)
    {
      bool retValue = base.ProcessTabKey(Keys.Tab);
      while (this.CurrentCell.ReadOnly)
      {
        retValue = base.ProcessTabKey(Keys.Tab);
      }
      return retValue;
    }
  }
}