Make the user required to enter text in a InputQuery.

Try this way:

procedure TForm1.FileBtnClick(Sender: TObject);
var aText: string;
begin
  aText := '';
  if (TreeView1.Selected <> nil) and (TreeView1.Selected.ImageIndex = 15) then
  begin
     if InputQuery('File', 'Enter a file name', aText) then
        begin
        if lenght(trim(aText)) > 0 then  AddItem(aText, 17, TreeView1.Selected)
        else Showmessage('You must enter a file name');
     end;  
  end else
    ShowMessage('Select a folder in the treeview first.');
end;
(*---------------------------------------------------*)
procedure TForm1.FolderBtnClick(Sender: TObject);
var aText: string;
  aParent: TTreeNode;
begin
  aParent := nil;
  if TreeView1.Selected <> nil then
  begin
    if TreeView1.Selected.ImageIndex = 15 then
      aParent := TreeView1.Selected
    else
    begin
      ShowMessage('Select a folder first');
      Exit;
    end;
  end;
  if InputQuery('Folder', 'Enter a folder name', aText) then
      begin
      if lenght(trim(aText)) > 0 then  AddItem(aText, 15, aParent)
      else Showmessage('You must enter a folder name');
  end;      
end;

Oke, one little thing.

When the user puts nothing in the editbox, the message will appear
the user than click the ok-button of the message and the message will go away.
But also the InputQuery, and that has to stay!

Peter

And I want to use a MessageBox, because i want a iconinformation it.
just like the picture.

Greetings, Peter Kiers

Thank you for your responce. Ill be back in an hour to try your example.

b.t.w: it's possible because the picture I posted is from another application
that works like that.

PK

I have tried your example and its not want i wanted.

In steps:
1. The user clicks on the folder button, to make a folder node.
2. The input-query appears where the user can enter a name for the node and the press OK
3. The user must put some text in the input-query, because when he doesn't en press OK
    a message appears
4. The user can click away the message by pressing ok, and the input-query is still there
    for enter the text of the node.

I adjust it a little bit:

procedure TForm1.FileBtnClick(Sender: TObject);
var aText: string;
begin
  aText := '';
  if (TreeView1.Selected <> nil) and (TreeView1.Selected.ImageIndex = 15) then
  begin
     if InputQuery('New Item', 'New Item Name:', aText) then
        begin
        if length(trim(aText)) > 0 then  AddItem(aText, 17, TreeView1.Selected)
        else MessageBox(0, 'You must enter an item name.', 'Error', MB_OK + MB_ICONEXCLAMATION);
     end;  
  end else
    ShowMessage('Select a folder in the treeview first.');
end;

procedure TForm1.FolderBtnClick(Sender: TObject);
var aText: string;
  aParent: TTreeNode;
begin
  aParent := nil;
  if TreeView1.Selected <> nil then
  begin
    if TreeView1.Selected.ImageIndex = 15 then
      aParent := TreeView1.Selected
    else
    begin
      ShowMessage('Select a folder first');
      Exit;
    end;
  end;
  if InputQuery('New Folder', 'New Folder Name:', aText) then
      begin
      if length(trim(aText)) > 0 then  AddItem(aText, 15, aParent)
      else MessageBox(0, 'You must enter a folder name.', 'Error', MB_OK + MB_ICONEXCLAMATION);
  end;
end;

The only problem with the procedures above is when the messagebox appears the Input-querie dissapears
Peter

I have also tested messagebox, messagedlg and showmessage but no success.
In either case InputQuery has disappeared.
I have little improved InputQuery, try this solution:

  private
    procedure ApplicationOnMessage(var Msg: TMsg; var Handled: Boolean);


in FormCreate event  put
    Application.OnMessage := Form1.ApplicationOnMessage;

procedure TForm1.ApplicationOnMessage(var Msg: TMsg; var Handled: Boolean);
var
  QEdit : TEdit;
  QLab : TLabel;
begin
  with Screen.ActiveForm do
     begin
     if (Caption =  'File')  or  
        (Caption =  'Folder') then
        begin
        QLab := Components[0] as TLabel;
        QEdt := Components[1] as TEdit;
        QEdt.Font.Color := clBlack;
        QLab.Font.Color := clBlack;
        QLab.Font.Style := [];
     end;
     if pos('ERROR', Caption) > 0  then
        begin
        QLab := Components[0] as TLabel;
        QEdt := Components[1] as TEdit;
        QEdt.Font.Color := clRed;
        QLab.Font.Color := clRed;
        QLab.Font.Style := [fsBold];
     end;
  end;
end;

procedure TForm1.FileBtnClick(Sender: TObject);
var aText: string;
begin
  aText := '';
  if (TreeView1.Selected <> nil) and (TreeView1.Selected.ImageIndex = 15) then
      begin
      InputQuery('File', 'Enter a file name', aText);
      if length(trim(aText)) = 0 then
         begin
         repeat
              if not (InputQuery('ERROR  - WRONG FILE NAME   !!! ', 'You must enter file name ', aText)) then Break;
         until length(trim(aText)) > 0;
      end;
      if length(trim(aText)) > 0 then  AddItem(aText, 17, TreeView1.Selected);
     end;  
  end else
    ShowMessage('Select a folder in the treeview first.');
end;

Thanks for the points.
regards,
 steve