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copied!<p>Just call it directly passing the param :</p> <pre><code>procedure TfmAPRBasedForm.TSDragEvent(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer); begin if something then dosomething else begin TButton(Sender.OnMouseDOwn) := OMDold // OMDold in most cases returns nil (not null) but its ok I just want to clear custom event from the object //line below is a point of my question - the one I used doesnt work If Assigned(TButton(Sender).OnMouseDown) then // Check if there is really an TMouseEvent TButton(Sender).OnMouseDown(Sender,Button,Shift,X,Y) //Call only when Event exist end; end; </code></pre> <p>You may need to changed the Button, Shift, X, Y though if you are using them in your OMDOld and you need the value other then current value in the dragEvent, like removing ssShift or so.</p> <p>If your OMDold is stored as TMethod then you can use :</p> <pre><code>TMouseEvent(OMDOld)(Sender,Button,Shift,X,Y); </code></pre> <p>Below is a full test example adjusted to show what you want to achieve in similar fashion :</p> <pre><code>Unit Unit4; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls; type TForm4 = class(TForm) btn1: TButton; btn2: TButton; procedure FormCreate(Sender: TObject); procedure btn1MouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer); procedure btn2MouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer); private { Private declarations } procedure NewMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer); public { Public declarations } OMDold : TMouseEvent; IsNew : Boolean; end; var Form4: TForm4; implementation {$R *.dfm} procedure TForm4.FormCreate(Sender: TObject); begin OMDold := btn1.OnMouseDown; btn1.OnMouseDown := NewMouseDown; IsNew := True; end; procedure TForm4.NewMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer); begin if IsNew then ShowMessage('New Method!') else if Assigned(OMDold) then OMDold(Sender,Button,Shift,X,Y); end; procedure TForm4.btn1MouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer); begin ShowMessage('Original Method!'); end; procedure TForm4.btn2MouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer); begin IsNew := not IsNew; end; end. </code></pre>

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