Fix Desktop file preview failing since v4.3.0 on Windows 10 LTSC

[Copilot]

Desktop file preview stopped working in v4.3.0+ on Windows 10 LTSC. The issue was traced to an overly strict cursor activation check in getSelectedFromDesktop() that caused false positives, preventing file path retrieval.

Changes

• Changed IsCursorActivated() check in Shell32::getSelectedFromDesktop() to pass 0 (null HWND) instead of the Desktop window handle
• This aligns the Desktop code path with the Explorer window pattern and checks the current thread state instead of the Desktop window's thread state
• The foreground window is already validated in GetFocusedWindowType(), making the Desktop window-specific check redundant and problematic

Before:

if (HelperMethods::IsCursorActivated(reinterpret_cast<HWND>(LongToHandle(phwnd))))
    return;  // False positive on LTSC - Desktop thread flags trigger early return

After:

if (HelperMethods::IsCursorActivated(0))
    return;  // Check current thread like Explorer path does

The Desktop window thread state on LTSC has UI flags set that inappropriately triggered the activation check, while passing 0 checks QuickLook's own thread state which is the correct context.

Original prompt

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This section details on the original issue you should resolve

<issue_title>previewing on Desktop Stopped working since ver 4.3.0</issue_title>
<issue_description>Bug:
I cannot preview anything on the desktop. Using the github version, no 3rd party extensions for desktop installed. I have reverted to version 3.7.3 and previewing works fine on desktop now.

To Reproduce
Steps to reproduce the behavior:

1. Go to Desktop
2. Click on a file

Expected behavior
Supported files should preview

• OS Version: Windows 10 LTSC
• QuickLook Version: 4.4.0

</issue_description>

<agent_instructions>帮我分析原因</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes previewing on Desktop Stopped working since ver 4.3.0 #1859

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