[SOLVED] Visual artifacts when showing a form inside a panel (Laz
1.2.6 Win32)
lazarus / 31-LCL

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lazjump · 2014-10-28 07:48

Hello,

I am currently making a Windows-only application where the user
interface is somewhat resembles the ribbon UI like in MS Office. But
my application is rather SDI, not MDI, because only one "child form"
could be visible at a time.

The main form have a Page Control on the top side, and a Panel below.
I put SpeedButtons on the TabSheets of the PageControl as menu
buttons. When a button clicked, then a corresponding child form is
created and displayed inside the Panel (Panel is the parent of the
child form).

Here is the method to create and show forms inside the panel:

Code: [Select]procedure TfMain.CreateAndShowForm(Form: TForm;
FormClass: TFormClass);
begin
  CloseActiveForm;

  Form:=FormClass.Create(Application);
  ActiveForm:=Form;

  Form.Parent:=pnlContent;
  Form.BorderStyle:=bsNone;
  Form.WindowState:=wsMaximized;
  Form.Show;

  Self.Caption:=Form.Caption;
end; 
The block of code above worked fine with Delphi 7.

But in Lazarus, it would cause visual artifacts like black borders
around buttons and another areas of the form beyond the original size
of the child form.

I had tinkered for some hours to find a workaround but I have not
succeed yet. So I would be glad if someone could help me to find a
workaround.

Here is the link to a sample project you can play with:

https://www.dropbox.com/s/vxur1pqou06yhsy/UI%20Test.7z?dl=0

I am using Lazarus 1.2.6 (with the FPC that comes with it) on Windows
XP SP2.

Thanks

EDIT: add code tags.

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taazz · 2014-10-28 08:51

try this one.
Code: [Select]procedure TfMain.CreateAndShowForm(Form: TForm;
FormClass: TFormClass);
begin
  CloseActiveForm;

  Form:=FormClass.Create(Application);
//  ActiveForm:=Form;

  Form.BorderStyle:=bsNone;
  Form.Align := alClient; //WindowState:=wsMaximized;
  Form.Parent:=pnlContent;
  Form.visible := True;

  Self.Caption:=Form.Caption;
end;

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lazjump · 2014-10-28 09:08

Wow! Thank you taazz! It works 

And we don't need to use the OnResize event of the main form anymore!

(I don't comment out ActiveForm:=Form; because the reference is still
needed).

Thanks again taazz