Bug: TPageControl.Anchors

[Handoko]

I prefer setting GUI components on runtime. Maintaining and inspecting becomes easier because I don't have to click the component and looking for the property in the Object Inspector.

But I've just found TPageControl.Anchors behaves weird. It works correctly if I set the Anchors on design time but not if I do it on runtime. Did I do it wrong?

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, Forms, Controls, Graphics, ComCtrls, StdCtrls;
9.  
10. type
11.  
12.   { TForm1 }
13.  
14.   TForm1 = class(TForm)
15.     Button1: TButton;
16.     Edit1: TEdit;
17.     PageControl1: TPageControl;
18.     TabSheet1: TTabSheet;
19.     TabSheet2: TTabSheet;
20.     TabSheet3: TTabSheet;
21.     procedure FormCreate(Sender: TObject);
22.   end;
23.  
24. var
25.   Form1: TForm1;
26.  
27. implementation
28.  
29. {$R *.lfm}
30.  
31. { TForm1 }
32.  
33. procedure TForm1.FormCreate(Sender: TObject);
34. begin
35.   PageControl1.Anchors := [akTop, akBottom, akLeft, akRight];
36.   Edit1.Anchors        := [akTop, akLeft, akRight];
37.   Button1.Anchors      := [akBottom, akLeft, akRight];
38. end;
39.  
40. end.

I tested it on Lazarus 2.0.10 GTK2 Ubuntu Mate. Can you reproduce the issue? Should I submit a bug report?

Below is the screenshot, left one - design time and right one - runtime:

[dseligo]

It seems fine on Windows 10, Laz 2.0.10.

[Michl]

I haven't looked in you app, but I think there is no bug, but not enough defined. I think you want to achieve something like this:

Code: Pascal  [Select][+][-]

1. procedure TForm1.FormCreate(Sender: TObject);
2. begin
3.   PageControl1.Anchors := [akTop, akBottom, akLeft, akRight];  
4.  
5.   // you have to set a control - if nil, parent is used
6.   Edit1.AnchorSideTop.Control := TabSheet1;
7.   Edit1.AnchorSideTop.Side := asrTop;
8.   Edit1.AnchorSideLeft.Control := TabSheet1;
9.   Edit1.AnchorSideLeft.Side := asrTop;
10.   // you can also use xyz.AnchorSide[akLeft], xyz.AnchorSide[akTop] etc.
11.   Edit1.AnchorSide[akRight].Control := TabSheet1;
12.   Edit1.AnchorSide[akRight].Side := asrBottom;
13.   // maybe, you want some space
14.   Edit1.BorderSpacing.Around := 10;    
15.   Edit1.Anchors        := [akTop, akLeft, akRight];
16.  
17.   // for Button1 you have to do the same
18.   Button1.Anchors      := [akBottom, akLeft, akRight];
19. end;  

See https://wiki.lazarus.freepascal.org/Anchor_Sides

[wp]

Without wanting to explicitly anchor all sides of the controls as in Michl solution, I think that the OnCreate event is too early. There are many properties which do not yet have their final values, and this may depend in detail on the widgetset.

But if I apply the anchoring commands later in the OnActivate event everything works fine.

[Handoko]

Ok, I understood now. Thank you all.