QSplitter would not show previously collapsed widgets.

After deleting or hiding the last non collapsed item in a QSplitter, none would
be visible. We now check wether there is any non-hidden, collapsed widget, and
set it to non-collapsed. Auto-test included.

Task-number: QTBUG-4101
Reviewed-by: Olivier

2 files changed, 49 insertions, 2 deletions

diff --git a/src/gui/widgets/qsplitter.cpp b/src/gui/widgets/qsplitter.cpp
index e3121ae..520a802 100644
--- a/src/gui/widgets/qsplitter.cpp
+++ b/src/gui/widgets/qsplitter.cpp
@@ -360,13 +360,26 @@ void QSplitterPrivate::recalc(bool update)
       before a hidden widget must be hidden.
     */
     bool first = true;
+    bool allInvisible = n != 0;
     for (int i = 0; i < n ; ++i) {
         QSplitterLayoutStruct *s = list.at(i);
-        s->handle->setHidden(first || s->widget->isHidden());
-        if (!s->widget->isHidden())
+        bool widgetHidden = s->widget->isHidden();
+        if (allInvisible && !widgetHidden && !s->collapsed)
+            allInvisible = false;
+        s->handle->setHidden(first || widgetHidden);
+        if (!widgetHidden)
             first = false;
     }
 
+    if (allInvisible)
+        for (int i = 0; i < n ; ++i) {
+            QSplitterLayoutStruct *s = list.at(i);
+            if (!s->widget->isHidden()) {
+                s->collapsed = false;
+                break;
+            }
+        }
+
     int fi = 2 * q->frameWidth();
     int maxl = fi;
     int minl = fi;
diff --git a/tests/auto/qsplitter/tst_qsplitter.cpp b/tests/auto/qsplitter/tst_qsplitter.cpp
index cf16421..b832f3a 100644
--- a/tests/auto/qsplitter/tst_qsplitter.cpp
+++ b/tests/auto/qsplitter/tst_qsplitter.cpp
@@ -102,6 +102,8 @@ private slots:
     void task187373_addAbstractScrollAreas();
     void task187373_addAbstractScrollAreas_data();
     void task169702_sizes();
+    void taskQTBUG_4101_ensureOneNonCollapsedWidget_data();
+    void taskQTBUG_4101_ensureOneNonCollapsedWidget();
 
 private:
     void removeThirdWidget();
@@ -1281,6 +1283,8 @@ class MyFriendlySplitter : public QSplitter
 public:
     MyFriendlySplitter(QWidget *parent = 0) : QSplitter(parent) {}
     void setRubberBand(int pos) { QSplitter::setRubberBand(pos); }
+
+    friend class tst_QSplitter;
 };
 
 void tst_QSplitter::rubberBandNotInSplitter()
@@ -1403,5 +1407,35 @@ void tst_QSplitter::task169702_sizes()
     QCOMPARE(testW->size().height(), testW->minimumSizeHint().height());
 }
 
+void tst_QSplitter::taskQTBUG_4101_ensureOneNonCollapsedWidget_data()
+{
+    QTest::addColumn<bool>("testingHide");
+
+    QTest::newRow("last non collapsed hidden") << true;
+    QTest::newRow("last non collapsed deleted") << false;
+}
+
+void tst_QSplitter::taskQTBUG_4101_ensureOneNonCollapsedWidget()
+{
+    QFETCH(bool, testingHide);
+
+    MyFriendlySplitter s;
+    QLabel *l;
+    for (int i = 0; i < 5; ++i) {
+        l = new QLabel(QString("Label ") + QChar('A' + i));
+        l->setAlignment(Qt::AlignCenter);
+        s.addWidget(l);
+        s.moveSplitter(0, i);  // Collapse all the labels except the last one.
+    }
+
+    s.show();
+    if (testingHide)
+        l->hide();
+    else
+        delete l;
+    QTest::qWait(100);
+    QVERIFY(s.sizes().at(0) > 0);
+}
+
 QTEST_MAIN(tst_QSplitter)
 #include "tst_qsplitter.moc"