diff --git a/src/corelib/doc/snippets/qloggingcategory/main.cpp b/src/corelib/doc/snippets/qloggingcategory/main.cpp
index b8483087c84..33aba3bf354 100644
--- a/src/corelib/doc/snippets/qloggingcategory/main.cpp
+++ b/src/corelib/doc/snippets/qloggingcategory/main.cpp
@@ -1,4 +1,4 @@
-// Copyright (C) 2016 The Qt Company Ltd.
+// Copyright (C) 2022 The Qt Company Ltd.
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
 
 #include <QCoreApplication>
@@ -39,15 +39,20 @@ void myCategoryFilter(QLoggingCategory *);
 //![20]
 
 //![21]
-QLoggingCategory::CategoryFilter oldCategoryFilter;
+static QLoggingCategory::CategoryFilter oldCategoryFilter = nullptr;
 
 void myCategoryFilter(QLoggingCategory *category)
 {
-    // configure driver.usb category here, otherwise forward to to default filter.
+    // For a category set up after this filter is installed, we first set it up
+    // with the old filter. This ensures that any driver.usb logging configured
+    // by the user is kept, aside from the one level we override; and any new
+    // categories we're not interested in get configured by the old filter.
+    if (oldCategoryFilter)
+        oldCategoryFilter(category);
+
+    // Tweak driver.usb's logging, over-riding the default filter:
     if (qstrcmp(category->categoryName(), "driver.usb") == 0)
         category->setEnabled(QtDebugMsg, true);
-    else
-        oldCategoryFilter(category);
 }
 //![21]
 
@@ -60,8 +65,6 @@ int main(int argc, char *argv[])
 //![2]
 
 //![22]
-
-// ...
 oldCategoryFilter = QLoggingCategory::installFilter(myCategoryFilter);
 //![22]
 
diff --git a/src/corelib/io/qloggingcategory.cpp b/src/corelib/io/qloggingcategory.cpp
index 1a84f6359cf..08b7b2d5848 100644
--- a/src/corelib/io/qloggingcategory.cpp
+++ b/src/corelib/io/qloggingcategory.cpp
@@ -343,13 +343,27 @@ QLoggingCategory *QLoggingCategory::defaultCategory()
 */
 
 /*!
-    Installs a function \a filter that is used to determine which categories
-    and message types should be enabled. Returns a pointer to the previous
-    installed filter.
+    \brief Take control of how logging categories are configured.
 
-    Every QLoggingCategory object created is passed to the filter, and the
-    filter is free to change the respective category configuration with
-    \l setEnabled().
+    Installs a function \a filter that is used to determine which categories and
+    message types should be enabled. If \a filter is \nullptr, the default
+    message filter is reinstated. Returns a pointer to the previously-installed
+    filter.
+
+    Every QLoggingCategory object that already exists is passed to the filter
+    before \c installFilter() returns, and the filter is free to change each
+    category's configuration with \l setEnabled(). Any category it doesn't
+    change will retain the configuration it was given by the prior filter, so
+    the new filter does not need to delegate to the prior filter during this
+    initial pass over existing categories.
+
+    Any new categories added later will be passed to the new filter; a filter
+    that only aims to tweak the configuration of a select few categories, rather
+    than completely overriding the logging policy, can first pass the new
+    category to the prior filter, to give it its standard configuration, and
+    then tweak that as desired, if it is one of the categories of specific
+    interest to the filter. The code that installs the new filter can record the
+    return from \c installFilter() for the filter to use in such later calls.
 
     When you define your filter, note that it can be called from different threads; but never
     concurrently. This filter cannot call any static functions from QLoggingCategory.
@@ -357,6 +371,10 @@ QLoggingCategory *QLoggingCategory::defaultCategory()
     Example:
     \snippet qloggingcategory/main.cpp 21
 
+    installed (in \c{main()}, for example) by
+
+    \snippet qloggingcategory/main.cpp 22
+
     Alternatively, you can configure the default filter via \l setFilterRules().
  */
 QLoggingCategory::CategoryFilter