How do I limit typing in a ComboBox Dropdown list

Question

I’ve created a form and added a ComboBox which generated the code:
this->DateList = (gcnew System::Windows::Forms::ComboBox());
this->SuspendLayout();
// DateList
this->DateList->Font = (gcnew System::Drawing::Font(L"Microsoft Sans Serif", 12,
System::Drawing::FontStyle::Bold, System::Drawing::GraphicsUnit::Point,
static_cast<System::Byte>(0)));
this->DateList->FormattingEnabled = true;
this->DateList->Location = System::Drawing::Point(91, 7);
this->DateList->Name = L"DateList";
this->DateList->Size = System::Drawing::Size(121, 28);
this->DateList->TabIndex = 0;
this->DateList->SelectedIndexChanged += gcnew System::EventHandler(this,&Form1::DateList_SelectedIndexChanged);
And then I added some custom code to add the items to the DateList
for ( int x = numSnapShots - 1 ; x >= 0 ; x-- )
  String ^ item = gcnew String ( SnapShots[x]->dateStr );
    this->DateList->Items->Add(item);
this->DateList->SelectedIndex = 0;
All is working fine, I can select any Snapshot date I want from the list. 
The problem is that I can also type anything I want in the ComboBox. 
The dropdown of 12/31/2014 is in the list, but I can also type “Last Year” and of course the code doesn’t know how to handle that.
What item in the combobox do I have the change to what to disable the user’s ability to type in the combobox?

Answer 1

David,
Maybe I didn’t look hard enough, but I could not find a way to create a C# WinForms project and include my existing C++ code as is and then interface the form front end to the existing C++ logic.
I did find relatively easy ways for a C++ CLI Windows Forms Application to communicate with standard C++. 
I had to limit the data types that I passed pack and forth, but the link up was relatively easy.
I have externals in Form1.h which can then simply call the primary C++ interface:
extern std::string str;
extern std::string strPage;
extern std::string strDate;
extern
void Initialize();
extern
int RebuildPage(int);
Initialize() is called right after Initialize Component() to load all the data into memory and build the first HTML page.
if (RebuildPage(7))    
RefreshThePage();
Exists for most of the button clicks and dropdown selections. 
The number tells the C++ code what form control was clicked and a nonzero return tells the form to refresh the page. 
Refresh the page is a simple Form1.h method that does just that, changes the labels on the form header and refreshes the HTML string to the new HTML data created by the C++ logic.
void RefreshThePage(void)
this->webBrowser1->DocumentText =
gcnew String( str.c_str() );
this->ViewLabel->Text =
gcnew String( strPage.c_str() );
this->DateLabel->Text =
gcnew String( strDate.c_str() );
This allowed me to perform all of the complex operation in the existing code with minimal changes, like changing the fprintf’s that created the original HTML files into str.append logic to pass the pages directly to the form.
It’s true that all of my other code was batch style console applications, but the form front end was not totally difficult to learn and the simple fixes like David Lowndes just suggested makes the coding even easier. 
Thanks again Dave.
I created a very complex program to make visualizing mutual fund trends very simple. 
The problem with the batch console application was that if I wanted to stop highlighting symbol ABC and wanted to start highlighting XYZ, I had to modify a data file by hand and then rerun the batch process to recreate the entire website on my local
drive so I could not instantly see the change.  Using a form front end and building and displaying the pages interactively make that process instant.