C# combobox (search anywhere within list, not just first letter )

you are right , combo box is really designed to represent short lists with simple and fast navigation.

but, client requirement is also not negligible because after all they are end users
In most of erp system client ask for this kind of searching facility
like while he writing customer-name = 'aar' then it gives customer-name start with 'aar' or having 'aar' in between string.

so, As my point of view it is common and popular problem :)

I never saw customers who demanded that his should be a combo box, and this should be a list box, etc. Most of them don't recognize exact control types. Reasonable users refer more to the ultimate goals and application aspects. They remember about particular controls only if the UI is not good enough, unclear, inconvenient, etc. See the point? The developers usually decides. The user never knows how exactly things should look, so it's the most important thing to offer right features at right moment. Do you see my point?
—SA

yes I agree, client doesn't have matter with a control he/she always talk regarding Facility.

Interesting thing is they ask for suggession-pop up and it is available in

textbox # autocomplete(but for developer it is string collection so for key-value scenario developer will avoid to use that one)

Combobox is also autocomplete and popup suggestions having ability for keeping both key and value. so, that developer(Not client) usually expect this kind of search from combobox.

and that's why OP is asking for combobox
all features are meeting just one to modify that popup display the records as per filtration scheme that can be override over the default one.

so, OP is asking for this also I am eager to know is it possible?
because right now I am redirecting user to new window for filtering data on key press. and client said please do something that I can get a popup not a new window... :)

you have more experience then us
so please answer could be possible with combobox
if yes(then how(override some events or other way to make make a control that can popup details like combobox doing)?)
or not possible?

To start with, I would like to know the type of ComboBox. OP needs to specify the UI library. There is more than one class named like this. Which one? :-)

In all cases, it's quite possible to create a fully custom control from scratch, derived from ?.?.?.Control class.
—SA