The phrase “capture the mouse” refers to the way
VB6 handles mouse events. By default, VB forms and controls capture the mouse,
and this behavior can affect the way your users make use of the mouse.

If you’re wondering what “capture” really means in
this context, here are two sample scenarios that will make it clearer.

Scenario 1:
Suppose that the user presses and releases the mouse button while the pointer
is over a specific control. The control fires the following events in order: MouseDown, MouseUp, Click.

Scenario 2: Now
imagine that the user presses the mouse button while the pointer is on the
control, moves the pointer off the control onto the form, and then releases the
button. You might expect that the control would receive a MouseDown
event and then the form would receive a MouseUp
event. It sounds reasonable, but that’s not what happens.

When the mouse
button is pressed on a form or control, the mouse is captured, and the form or
control receives all mouse events including MouseMove
events up to and including the next MouseUp—no matter
where the pointer is moved.

Thus, in Scenario 2, the PictureBox
receives the MouseDown event, a series of MouseMove events, and the final MouseUp
event; the form receives no mouse events at all. There is no Click event in
this situation.

You can verify this behavior for yourself by creating a
simple project with one control on the form and then using Debug. Print
statements in the various mouse event procedures to track the events that

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