Friday, August 10, 2007

I just wanted to use a listbox

I just wanted to use a listbox. How hard could that be? Harder than I thought:

I’ve recently decided to try my hand at writing programs for Windows Mobile Smartphones. I had an idea for a program and wanted to see if I could use the Compact Framework 2.0 and get it to work.

One of the main components of my program is a list. So, not surprisingly, I wanted to use a listbox. But it turns out that the version of the Compact Framework for Smartphones doesn’t have a listbox control.

So, I figured: “Oh well, I’ll just have to use a listview control set to List mode.”

(I first met listview controls in VB 6; didn’t like ‘em then and I’m still not too fond of ‘em now. I guess I never cared for the way they handle multicolumn lists – I found subitems to be a pain. But for this project I just needed a single column list.)

Now, in regular .Net a listbox control can hold objects -- as long as the objects implement a .ToString() method. The listbox uses this method to determine what to display in the list. This is exactly what I needed. Unfortunately, listview controls don’t just hold any arbitrary object. Instead they hold listviewitem objects.

So, I tried creating a new object that was derived from a listviewitem object. I planned on adding methods and properties to support my needs. I overrode the .ToString() method and found that listviewitems don’t use .ToString() to determine what text to display in the listview. Instead they have a .Text property. No, problem. I’ll just override the .Text property. Guess what? Listviewitem’s .Text property isn’t overridable!!!


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