Articles   Members Online:
-Article/Tip Search
-News Group Search over 21 Million news group articles.
-Delphi/Pascal
-CBuilder/C++
-C#Builder/C#
-JBuilder/Java
-Kylix
Member Area
-Home
-Account Center
-Top 10 NEW!!
-Submit Article/Tip
-Forums Upgraded!!
-My Articles
-Edit Information
-Login/Logout
-Become a Member
-Why sign up!
-Newsletter
-Chat Online!
-Indexes NEW!!
Employment
-Build your resume
-Find a job
-Post a job
-Resume Search
Contacts
-Contacts
-Feedbacks
-Link to us
-Privacy/Disclaimer
Embarcadero
Visit Embarcadero
Embarcadero Community
JEDI
Links
How can I force a drop-down combo to drop its list down Turn on/off line numbers in source code. Switch to Orginial background IDE or DSP color Comment or reply to this aritlce/tip for discussion. Bookmark this article to my favorite article(s). Print this article
27-Dec-02
Category
VCL-General
Language
Delphi 2.x
Views
136
User Rating
No Votes
# Votes
0
Replies
0
Publisher:
DSP, Administrator
Reference URL:
DKB
			Author: Lou Adler

How can I force a drop-down combo to drop its list down?

Answer:

This is done by using a Windows message called CB_SHOWDROPDOWN.

I recommend that you look in the WinAPI help under messages to see what else you 
can do with them.

The nice thing about messaging in Windows is that the calls are all handled through 
the Windows API SendMessage routine, which requires four parameters:

Parameters of SendMessage function
Window Handle (can be an object handle)
Message  specifies the message to be sent (in our case, CB_SHOWDROPDOWN)
wParam, a 16-bit message-dependent parameter
lParam, a 32-bit message-dependent parameter (see WinHelp for specifics on what 
goes into wParam and lParam)

The gist of this is that Windows messages are performed in a very standard way, so 
if you haven't done them much, I encourage you to investigate ways to employ them 
in your code.

To get a combo-box list to automatically drop down when you enter it, put the 
following code into the OnEnter event:
1   
2   procedure TForm1.ComboBox1Enter(Sender: TObject);
3   begin
4     SendMessage(ComboBox1.handle, CB_SHOWDROPDOWN, Integer(True), 0);
5   end;


Likewise, you can close the drop-down when you exit by putting the following code 
into the OnExit event of the combo box:
6   
7   procedure TForm1.ComboBox1Exit(Sender: TObject);
8   begin
9     SendMessage(ComboBox1.handle, CB_SHOWDROPDOWN, Integer(False), 0);
10  end;


This is probably how the Intuit guys did it with Quicken. So go for it!

			
Vote: How useful do you find this Article/Tip?
Bad Excellent
1 2 3 4 5 6 7 8 9 10

 

Advertisement
Share this page
Advertisement
Download from Google

Copyright © Mendozi Enterprises LLC