DBT_QUERYCHANGECONFIG event

The system broadcasts the DBT_QUERYCHANGECONFIG device event to request permission to change the current configuration (dock or undock). Any application can deny this request and cancel the change.

To broadcast this device event, the system uses the WM_DEVICECHANGE message with wParam set to DBT_QUERYCHANGECONFIG and lParam set to zero.

LRESULT CALLBACK WindowProc(
  HWND hwnd,       // handle to window
  UINT uMsg,       // WM_DEVICECHANGE
  WPARAM wParam,   // device-change event
  LPARAM lParam    // event-specific data
);

Parameters

hwnd

A handle to a window.

uMsg

The WM_DEVICECHANGE message identifier.

wParam

Set to DBT_QUERYCHANGECONFIG.

lParam

Set to zero.

Return value

Return TRUE to grant permission to change the configuration.

Return BROADCAST_QUERY_DENY to deny permission to change the configuration.

Requirements

Requirement	Value
Minimum supported client	Windows XP
Minimum supported server	Windows Server 2003
Header	Dbt.h

See also

Device Events

Device Management Events

WM_DEVICECHANGE