Showing a tooltip for a MenuItem

Tooltip is set manually by:

testToolStripMenuItem2.ToolTipText = "My tooltip text";

The MenuItem can for example be part of this menu constellation: a menu strip with a menu item and a sub menu item. (This plumbing code is generated automatically for you in the code behind designer file if you use visual studio)

MenuStrip menuStrip1;    
ToolStripMenuItem testToolStripMenuItem; // Menu item on menu bar
menuStrip1.Items.Add(testToolStripMenuItem);

ToolStripMenuItem testToolStripMenuItem2; // Sub menu item
testToolStripMenuItem.DropDownItems.Add(testToolStripMenuItem2)

On the MenusTrip set "ShowItemToolTips = True" and on the ToolStripMenuItem set your ToolTipText

yourMenuStrip.ShowItemToolTips = true;
yourToolStripMenuItem.ToolTipText = "some txt";

If you are creating your menu items using the System.Windows.Forms.MenuItem class you won't have a "ToolTipText" property.

You should use the System.Windows.Forms.ToolStripMenuItem class which is new as of .Net Framework 2.0 and DOES include the "ToolTipText" property.

You also have to remember to specify ShowItemToolTips = True on the MenuStrip control

May be that I misunderstood you problem, but why do you need to use the Tooltip class? You can assign your text to the ToolTipText property and it will be shown to the user.