Help with design of "draggable" or "drag-over" button or hot-spot.

[markszlazak]

We are all familiar with "no-drag" displaying when one tries to drag
over a _fixed_ web-page image.

No-drag won't display if you start dragging (start mousedown) just
outside the image before moving over it because the operation is a
selection of the image. However starting the mousedown in the image
and then dragging over it will cause "no-drag" to appear.

I can only drag-select certain fixed elements like table cells,
textareas, whole images, input boxes, etc. What I want is a table
where each cell has a small "button" or hot-spot in it's top-right
corner. This "button", when mousedowned on, starts a different
operation mode on the table where you can then drag over the button,
down a column of table cells and then release (mouseup) anywhere over
a table cell of the same column, thus selecting (highlighting) all the
dragged over table cells.

So, I'm wondering what is the best way to make a dragged-over start-
selection-button/spot.

I wanted this button to change image with mousedown but that won't
work so changing color and text would be nice if doable.

Any suggestions?

Thanks