c# - How can I prevent auto-select in ComboBox on drop-down except for exact matches? -

i have combobox part of detail display related data grid containing rows database. no binding combobox exists, doing manually. combobox allows manual entry, if text field, while still providing drop-down of choices.

my issue if have manually entered text in field, , drop-down clicked, combobox apparently wants seek out match. also, appears search simple, kg matches kg/day. must avoid , force exact match.

but further, think need able govern entire process myself, because further complicate matter, drop-down item read kg/day - kilograms/day. database field data fetched, however, storing portion prior hyphen, kg/day.

so, need intercept drop-down action in way allows me 2 things:

1) perform own search find whether or not have ad-hoc text, or "real" match. in selected drop-down; in other words, have kg/day , not kg.

2) eliminate auto-search behavior combobox wants do.

i have tried getting in front of these things using method handlers in form, such

combobox::dropdown() , combobox::dropdownclosed(),

but seems these still don't allow me stop basic combobox searching/matching.

i have tried creating class of own inherited combobox, don't know override, or in general how go getting want, stopping don't.

so, that, thank advice.

edit: expand on tried already... in inherited class, attempting use wndproc override. based on advice found in forum, goal intercept combobox message lb_findstring , replace lb_findstringexact. post suggested combobox defaulted lb_findstring, fits see doing, , subbing lb_findstringexact cure problem. trouble is, unless got bad definition lb_findstring, never received.

here's enum:

[flags] public enum listboxflags {     lb_addstring = 0x0180,     lb_setsel = 0x0185,     lb_getselitems = 0x0191,     lb_getselcount = 0x0190,     lb_getcursel = 0x0188,     lb_selectstring = 0x018c,     lb_setcursel = 0x0186,     lb_findstring = 0x018f,     lb_findstringexact = 0x01a2,     lb_getcount = 0x018b,     lb_getsel = 0x0187,     lb_gettext = 0x0189,     lb_resetcontent = 0x0184,     lb_sethorizontalextent = 0x0194,     lb_gethorizontalextent = 0x0193,     lb_gettopindex = 0x018e,     lb_settopindex = 0x0197,     lb_insertstring = 0x0181,     lb_deletestring = 0x0182,     lb_getitemdata = 0x0199 } 

made sample code might - can use guide.

the idea handle textchanged event of combobox, , modify combobox list items @ point. example below modify list add current text (most important, not change text when click combobox) , other items meet search criteria.

i don't think need code re-initialize list items when focus lost, left in there in case.

    //contains list of default items combobox items     list<string> combolist = new list<string>();      public form1()     {         initializecomponent();         initcombolist(); //initialize defaults         initcombobox(); //initialize combobox list items     }      //fills defaults combobox items     private void initcombolist()     {         combolist.add("red");         combolist.add("blue");         combolist.add("green");     }      //initializes combobox items     private void initcombobox()     {         combobox1.items.clear();         foreach (string s in combolist)             combobox1.items.add(s);     }      //occurs when text changes in combobox     private void combobox1_textchanged(object sender, eventargs e)     {         string curtext = combobox1.text;         insertintocombobox(curtext);   //insert current text combobox         combobox1.select(curtext.length, 0); //if don't this, cursor goes index 0 :-(     }      //called whenever desired insert current text combobox items     private void insertintocombobox(string curtext)     {         combobox1.items.clear();         //only add current text if it's not in list of defaults , not empty string         if (combolist.contains(curtext) == false && curtext.length > 0)             combobox1.items.add(curtext);         foreach (string s in combolist)                 combobox1.items.add(s);     }      //called whenever combobox loses focus     private void combobox1_leave(object sender, eventargs e)     {         initcombobox();     }