[Overview][Constants][Types][Classes][Procedures and functions][Variables][Index] | Reference for unit 'Dialogs' (#lcl)

# TCustomTaskDialog.OnHelp

Event handler signalled to display help for the task dialog.

## Declaration

Source position: dialogs.pp line 856

`public property TCustomTaskDialog.OnHelp : TNotifyEvent read FOnHelp write FOnHelp;`

## Description

OnHelp is a TNotifyEvent property with the event handler signalled to display help for the task dialog. It is signalled (when assigned) from the DoOnHelp method.

For native implementations using the Task Dialog API (supported Windows versions), it occurs when the TDN_HELP notification is handled in the callback routine for the class instance. For emulated task dialog forms, it occurs when the F1 key is processed in the KeyDown handler for the LCL form instance.

Applications can implement and assign a routine to the handler to perform the actions needed to display context or keyword help for the dialog.

## Version info

Added in LCL version 4.0.

## See also

TCustomTaskDialog.DoOnHelp |  | Signals the OnHelp event handler (when assigned).
TLCLTaskDialog.KeyDown |  | Implements the OnKeyDown event handler for the task dialog.