Multiselect listbox items by dragging the mouse but not using control key

Try this.

listBox1.SelectionMode = SelectionMode.MultiExtended;

Using SelectionMode = MultiSimple seems to work like you describe.

If you really want to select different items in listbox , then why not use CheckedListBox?

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It is possible to simulate click-drag-rectangle selection over a WinForms collection-container control, but to do it, you are going to have to use an overlay of a transparent something: if that something is a Panel you make transparent via over-riding 'CreateWindowEx using the 'WS_EX_TRANSPARENT setting, you're probably not going to be satisfied, visually, with the result; if that something is a Form, you can set the opacity of the Form to give you good visual feedback.

To implement this solution means you are going to have to really "get down" with the ListBox control, and figure out how to detect where the MouseDown that triggers selection is, and, on MouseUp, you are going to need to iterate the rows of the ListBox and test for 'containment' in the bounding box of the selection rectangle at the time of MouseUp.

This is non-trivial, and may require you to handle some quirks of the ListBox ... which are unknown to me ... so I can't say with confidence doing this would meet your needs: I have implemented this on a TreeView, and it works, but use caution if you pursue this strategy.

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In your message title, you imply you do not want to drag the mouse, but in the body of your message, you mention dragging ... that's kind of ambiguous ... so ...

I think what you are saying here is that you want the option to mouse-down on a row, and then click-drag a selection rectangle, and, when you mouse-up, then all rows within the selection rectangle are selected.

Some commercial .NET List-type controls support such selection-rectangle use, like one I use now.

If you want this selection-rectangle facility with the 'native' Windows .NET ListBox control ... that means you are going to actually need to draw a selection rectangle yourself, and compute the intersection with rows, then select them.

It may mean you will need to sub-class the native Windows ListBox, and handle the Paint event yourself; perhaps a daunting task ?

But, there may well be an owner-drawn sub-class of the old COM-based .NET ListBox here on CodeProject, or an example of using a selection rectangle with some other type of collection-manager control which you could apply to a ListBox: it's worth searching for.

good luck, Bill

Hi Everyone,

I would like to thank everyone who gave their idea to help me. The concept given by Mr BillWoodruff works perfectly for me ...hold the control-key down and I can pick rows at random and I can also click a row and drag to select new rows.

Thanks again