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# Known Issues in 4.5.2

An up-to-date list of known issues with Qt 4.5.2 can be found via the Task Tracker on the Qt website which provides additional information about known issues and tasks related to Qt.

### General Issues

When running Qt applications on Windows or with `-graphicssystem raster`, any process that triggers a QWidget::update() from within a destructor might result in a crash.

### Issues with Third Party Software

#### X11 Hardware Support

- There is a bug in the 169.xx NVIDIA drivers on certain GeForce 8 series cards that is triggered by the OpenGL paint engine when using QPainter on a QGLWidget to draw paths and polygons. Some other painting operations that end up in the path fallback are affected as well. The bug causes the whole X server to repeatedly hang for several seconds at a time.
- There is an issue with NVIDIA's 9xxx driver series on X11 that causes a crash in cases where there are several QGLContexts and the extended composition modes are used (the composition modes between and including QPainter::CompositionMode_Multiply and QPainter::CompositionMode_Exclusion). This affects the composition mode demo in Qt 4.5, for example. The crash does not occur in newer versions of the drivers.

#### Windows Hardware Support

- When using version 6.14.11.6921 of the NVIDIA drivers for the GeForce 6600 GT under Windows XP, Qt applications which use drag and drop will display reduced size drag and drop icons when run alongside applications that use OpenGL. This problem can be worked around by reducing the level of graphics acceleration provided by the driver, or by disabling hardware acceleration completely.

#### Windows Software Issues

- When building Qt 4.5.0 with Windows 7, the build fails with an error message regarding failing to embed manifest. This a known issue with Windows 7, explained in the Windows 7 SDK Beta release notes. A workaround for this issue is to patch the embed_manifest_exe.prf file with the following:

       diff --git a/mkspecs/features/win32/embed_manifest_exe.prf b/mkspecs/features/win32/embed_manifest_exe.prf
       index e1747f1..05f116e 100644
       --- a/mkspecs/features/win32/embed_manifest_exe.prf
       +++ b/mkspecs/features/win32/embed_manifest_exe.prf
       @@ -8,4 +8,9 @@ if(win32-msvc2005|win32-msvc2008):!equals(TEMPLATE_PREFIX, "vc"):equals(TEMPLATE
            QMAKE_POST_LINK = $$quote(mt.exe -nologo -manifest \"$$replace(OBJECTS_DIR,/,\\)\\$${NOPATH_TARGET}.intermediate.ma
       nifest\" -outputresource:$(DESTDIR_TARGET);1$$escape_expand(\n\t))
            QMAKE_POST_LINK += $$QMAKE_PREV_POST_LINK
            QMAKE_CLEAN += \"$$replace(OBJECTS_DIR,/,\\)\\$${NOPATH_TARGET}.intermediate.manifest\"
       +    isEmpty(RC_FILE) {
       +        system("echo.>$$replace(OUT_PWD,/,\\)\\$$replace(OBJECTS_DIR,/,\\)\\Windows7WorkAround.rc")
       +        RC_FILE = $$replace(OUT_PWD,/,\\)\\$$replace(OBJECTS_DIR,/,\\)\\Windows7WorkAround.rc
       +       }
       +
        }

- Under certain circumstances Visual Studio Integration v1.4.0 will not be able to install the integration for Visual Studio 2005 on Windows Vista. An error message states that .NET Framework v2.0 Service Pack 1 is not installed. This is due to a problem with the built-in installation of this on Windows Vista. This issue can be fixed by installing .NET Framework version 3.5.
- With NVIDIA GeForce 7950 GT (driver version 6.14.11.7824), a fullscreen QGLWidget flickers when child widgets are shown/hidden. The workaround for this is to use setGeometry() with a width/height 1 pixel bigger than your geometry and call show().
- A bug in the Firebird database can cause an application to crash when `fbembed.dll` is unloaded. The bug is fixed in version 2.5.

#### Mac OS X Software Support

- If a sheet is opened for a given window, clicking the title bar of that window will cause it to flash. This behavior has been reported to Apple (bug number 5827676).