If it has TControl as an ancestor then put:
published property OnDblClick;
into your class declaration.
Otherwise use the following code to capture the message:
type
TYourClass=class(WhatEverclass you want)
private
FOnDblClick : TNotifyEvent;
procedure WMDblClick(var :TWMLButtonDBLCLK);
message WM_LBUTTONDBLCLK;
// ..
public
OnDblClick : TNotifyEvent read FOnDblClick write FOnDblClick;
end;
// if you don't want a property OnDblClick
procedure TYourClass.WMDblClick(var :TWMLButtonDBLCLK);
begin
inherited;
// do your stuff here
end;
// or: if you do want a property OnDblClick
procedure TYourClass.WMDblClick(var :TWMLButtonDBLCLK);
begin
inherited;
if Assigned (FOnDblClick)
FOnDblClick(Self);
end;