Move point to where you click (@code{mouse-set-point}).
This is normally the left button.
+@vindex x-mouse-click-focus-ignore-position
+Normally, Emacs does not distinguish between ordinary mouse clicks and
+clicks that select a frame. When you click on a frame to select it,
+that also changes the selected window and cursor position according to
+the mouse click position. On the X window system, you can change this
+behavior by setting the variable
+@code{x-mouse-click-focus-ignore-position} to @code{t}. Then the
+first click selects the frame, but does not affect the selected window
+or cursor position. If you click again in the same place, since that
+click will be in the selected frame, it will change the window or
+cursor position.
+
@item Drag-Mouse-1
Set the region to the text you select by dragging, and copy it to the
kill ring (@code{mouse-set-region}). You can specify both ends of the
on how far away from the window edge the mouse has gone; the variable
@code{mouse-scroll-min-lines} specifies a minimum step size.
+@vindex mouse-drag-copy-region
+If the variable @code{mouse-drag-copy-region} is @code{nil}, this
+mouse command does not copy the selected region into the kill ring.
+
@item Mouse-2
Yank the last killed text, where you click (@code{mouse-yank-at-click}).
This is normally the middle button.