nvda

00c1ef51 - Only restore braille on secure desktop exit, not on ordinary desktop switches (#20550)

Only restore braille on secure desktop exit, not on ordinary desktop switches (#20550) Fixup for #18810 Summary of the issue: Since #18810, NVDA frees the braille display when switching to the secure desktop and restores it when returning to a user desktop. However, the restore branch also runs on desktop switches that never entered the secure desktop. Moving input focus between a Remote Desktop session and the local machine generates EVENT_SYSTEM_DESKTOPSWITCH in the remote session, so braille.handler._onSecureDesktopStateChanged is invoked with isSecureDesktop=False even though the secure desktop was never active. This re-runs braille display detection (or re-sets the configured display), repeatedly disconnecting and re-detecting a working display. For remote braille (e.g. RDAccess) each such switch causes a full channel teardown and re-handshake, so braille churns on every alt+tab / focus change. Description of user facing changes: The braille display is no longer briefly disconnected and re-detected on desktop switches that do not enter the secure desktop, such as switching between a Remote Desktop session and the local machine. Description of developer facing changes: None. Description of development approach: In BrailleHandler._onSecureDesktopStateChanged, when returning to a user desktop (isSecureDesktop=False), only restore the display when the current display differs from _lastRequestedDisplayName. Switching to the secure desktop replaces the display with the noBraille fallback via setDisplayByName(..., isFallback=True), which deliberately does not update _lastRequestedDisplayName. So a current display equal to _lastRequestedDisplayName means the display was never freed (an ordinary desktop switch) and there is nothing to restore. This covers both automatic detection (where _lastRequestedDisplayName holds the detected driver name) and a manually configured display (where it equals the configured display). Entering the secure desktop is unchanged, so the display is still freed there.