Author: Jonas Bilinkevicius 

How to make the [Enter] key behave like the [Tab] key

Answer:

Solve 1:

You need to trap the keystroke and set up your own response to it. Try this: (Note: 
This will not work within a DBGrid, since the next field is not a separate object.)

1   procedure TMainForm.FormCreate(Sender: TObject);
2   begin
3     keyPreview := true; {To turn the event "ON"}
4   end;
5   
6   procedure TMainForm.FormKeyPress(Sender: TObject; var Key: Char);
7   begin
8     if Key = #13 then
9     begin
10      Key := #0;
11      PostMessage(Handle, WM_NEXTDLGCTL, 0, 0);
12    end;
13  end;



Solve 2:

Use this code for example for an TEdit's OnKeyPress event:
14  
15  procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
16  begin
17    if Key = #13 then
18    begin
19      SelectNext(Sender as TWinControl, True, True);
20      Key := #0;
21    end;
22  end;


This causes Enter to behave like tab. Now, select all controls on the form you'd 
like to exhibit this behavior (not Buttons) and go to the Object Inspector and set 
their OnKeyPress handler to EditKeyPress. Now, each control you selected will 
process Enter as Tab. If you'd like to handle this at the form (as opposed to 
control) level, reset all the controls OnKeyPress properties to blank, and set the 
form's OnKeyPress property to EditKeyPress. Then, change Sender to ActiveControl 
and set the form's KeyPreview property to true:
23  
24  procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
25  begin
26    if Key = #13 then
27    begin
28      SelectNext(ActiveControl as tWinControl, True, True);
29      Key := #0;
30    end;
31  end;


This will cause each control on the form (that can) to process Enter as Tab.


Solve 3:

Handle this in the OnKeyPress event. The form's KeyPreview property must be set to 
true.

32  procedure TFrmEnterTab.FormKeyPress(Sender: TObject; var Key: Char);
33  begin
34    if Key = Chr(VK_RETURN) then
35    begin
36      if GetKeyState(VK_SHIFT) < 0 then
37        SelectNext(ActiveControl, false, true)
38      else
39        SelectNext(ActiveControl, true, true);
40      Key := #0;
41    end;
42  end;