asked on

"Control has no parent window" error message

Dear friends,

I'm developing a new component herited from a TreeView. I use a small application to test it since the very beginning without problem.
Today, when I drop the component from the palette to a new form, I got this message. Can you help me ?

Bob

ahalya

I think you can assign a parent in your control's create event;
e.g.

constructor TMyControl.Create(AOwner:TWinControl);

begin;
inherited Create;
Parent := AOwner;
....

aldyn

Likely you trying to do some operations (painting or something else that requires control's window handle) before the parent is set. Delay it until the SetParent will be called.

toesable

make sure you have this statement: inherited Create(AOwner); in your constructor.

Igor UL7AAjr

Avoid drawing if Parent = nil.

alexstewart@beta

Sounds like this is happening at design time.

try checking componentstate for csDesigning and that parent<>nil before doing stuff.

You might try removing and reinstalling the package too, since it might be 'stale' code (designtime<>runtime).

I sometimes override the paint method, to tell me when its ok to do stuff, I wait for the first call to paint.

Alex

ASKER CERTIFIED SOLUTION

apostolost

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

baudewyns

ASKER

Well, the problem is not coming from my Tree component but from the Header created by code which is a recent addition. If I remove this part of the code, it's working fine.

I have to look around to fix the bug.
Many thanks to all of you.

I accept the answer to close the file even if not really relevant.

&quot;Control has no parent window&quot; error message

"Control has no parent window" error message