What is the difference between mouseenter and mousehover?

Question

In a C# Windows application there are 2 different mouse events, MouseEnter and MouseHover, which are both triggered when the cursor is over the object.

What is the difference between them?

Answer 1

Assuming you are in Windows Forms:

Mouse Enter occurs:

Occurs when the mouse pointer enters the control.

(MSDN)

Mouse Hover:

Occurs when the mouse pointer rests on the control.

A typical use of MouseHover is to display a tool tip when the mouse pauses on a control within a specified area around the control (the "hover rectangle"). The pause required for this event to be raised is specified in milliseconds by the MouseHoverTime property.

(MSDN)

To set MouseHoverTime globally (not recommended, see @IronMan84's link here for a better solution), you can use the SystemParametersInfo function. Because thats a Win32 API call, you'll need PInvoke:

[DllImport("user32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool SystemParametersInfo(SPI uiAction, uint uiParam, IntPtr pvParam, SPIF fWinIni);

Called as:

SystemParametersInfo(SPI.SPI_SETMOUSEHOVERTIME, 
                     desiredHoverTimeInMs, 
                     null, 
                     SPIF.SPIF_SENDCHANGE );

Sigantures from PInvoke.NET: SystemParametersInfo, SPIF (Enum), SPI (Enum)

I didn't include the Enum signatures here because they are so freaking long. Just use the ones on PInvoke.Net (linked above)

For complete information on the SystemParametersInfo API call and its parameters, see MSDN.