CODEWITHSUNDEEP
winapishellwindows-xpwindow
Unsigned
Unsigned

Reputation: 9916

ShowWindowAsync doesn't activate a hidden+minimized window?

A given external (not owned by the current process) window (hWnd) is first minimized, then hidden:

ShowWindowAsync(hWnd, SW_MINIMIZE);
// wait loop inserted here
ShowWindowAsync(hWnd, SW_HIDE);

The following call properly restores it to the un-minimized (restored) state:

ShowWindow(hWnd, SW_RESTORE);

However, this call does not:

ShowWindowAsync(hWnd, SW_RESTORE);

In the second instance with ShowWindowAsync(), the window is un-minimized and no longer hidden, but it is not activated (remains behind other existing windows). Conversely, the first ShowWindow() call correctly activates the window.

Is this expected behavior? How can I restore the window (to the foreground) without relying on ShowWindow(), which is synchronous (blocking)? (The wait loop in the example can have a timeout, while ShowWindow() does not allow specification of a timeout.)

(WinXP SP3)

Upvotes: 1

Views: 2444

Answers (2)

Unsigned
Unsigned

Reputation: 9916

Here's the solution as used:

ShowWindowAsync(hWnd, SW_SHOW);
// wait loop inserted here
ShowWindowAsync(hWnd, SW_RESTORE);

This is essentially an inversion of the snippet used to hide the window:

ShowWindowAsync(hWnd, SW_MINIMIZE);
// wait loop inserted here
ShowWindowAsync(hWnd, SW_HIDE);

Upvotes: 1

Neil
Neil

Reputation: 55392

ShowWindowAsync posts a show-window event to the message queue of the given window. In particular, the window is shown by its thread, rather than your thread. And the difference is that your thread is the foreground thread, and can therefore activate another window, which it can't do itself.

Upvotes: 1

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