ChartBar drag fixup for Qt5.10 regression

.. When the widget in QScrollArea resizes the position is set to origin,
   which is a regression introduced sometime after Qt5.9.

.. If the chart bar was scrolled then dragging a tab would cause the
   buttonbar to be resized temporarily as the item is removed from one
   index and placed at another.

.. To get around this we make the buttonbar fixedWidth, which means no
   resize events or processing occurs. But it means we need to adjust
   as widgets are added and removed.

.. Fortunately an existing function 'tidy()' is available to do this for
   us, but needed to be controlled (only resize when widgets are added
   or removed).

.. If the regression is fixed this commit can be reverted, but it should
   be harmless with/without any Qt fix.

src/Charts/ChartBar.cpp

@@ -57,8 +57,8 @@ ChartBar::ChartBar(Context *context) : QWidget(context->mainWindow), context(con
 
     // scrollarea
     scrollArea = new QScrollArea(this);
-    scrollArea->setAutoFillBackground(false);
-    scrollArea->setWidgetResizable(true);
+    scrollArea->setAutoFillBackground(true);
+    scrollArea->setWidgetResizable(false);
     scrollArea->setFrameStyle(QFrame::NoFrame);
     scrollArea->setContentsMargins(0,0,0,0);
     scrollArea->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
@@ -149,6 +149,9 @@ ChartBar::configChanged(qint32)
     scrollArea->setFixedHeight(height);
     buttonBar->setFixedHeight(height);
 
+    QColor col=GColor(CCHROME);
+    scrollArea->setStyleSheet(QString("QScrollArea { background: rgb(%1,%2,%3); }").arg(col.red()).arg(col.green()).arg(col.blue()));
+
     foreach(ChartBarItem *b, buttons) {
         int width = fs.width(b->text) + (30 * dpiXFactor);
         if (width < (80*dpiXFactor)) width=80*dpiXFactor;
@@ -184,7 +187,7 @@ ChartBar::addWidget(QString title)
     newbutton->installEventFilter(this);
 
     // tidy up scrollers etc
-    tidy();
+    tidy(true);
 }
 
 void
@@ -209,20 +212,22 @@ ChartBar::setText(int index, QString text)
     buttons[index]->setWidth(width < (80*dpiXFactor) ? (80*dpiXFactor) : width);
     buttons[index]->update();
 
-    tidy(); // still fit ?
+    tidy(true); // still fit ?
 }
 
 
 // tidy up the scrollers on first show...
 void
-ChartBar::tidy()
+ChartBar::tidy(bool setwidth)
 {
     // resize to button widths + 2px spacing
-    int width = 2*dpiXFactor;
-    foreach (ChartBarItem *button, buttons) {
-        width += button->geometry().width() + (2*dpiXFactor);
+    if (setwidth) {
+        int width = 2*dpiXFactor;
+        foreach (ChartBarItem *button, buttons) {
+            width += button->geometry().width() + (2*dpiXFactor);
+        }
+        buttonBar->setFixedWidth(width);
     }
-    buttonBar->setMinimumWidth(width);
 
     if (buttonBar->width() > scrollArea->width()) {
         left->show(); right->show();
@@ -239,18 +244,18 @@ ChartBar::eventFilter(QObject *object, QEvent *e)
 
         // we do NOT move the position, we just show/hide
         // the left and right scrollers
-        tidy();
+        tidy(false);
     }
 
     // showing us - tidy up
     if (object == this && e->type() == QEvent::Show) {
-        tidy();
+        tidy(false);
     }
 
     // enter/leave we can track approximate mouse position and decide 
     // if we want to 'autoscroll'
     if (e->type() == QEvent::Leave || e->type() == QEvent::Enter) {
-        tidy(); // tidy up anyway
+        tidy(false); // tidy up anyway
     }
 
     return false;
@@ -319,6 +324,7 @@ ChartBar::removeWidget(int index)
     for (int i=0; i<buttons.count(); i++)
         signalMapper->setMapping(buttons[i], i);
 
+    tidy(true);
 }
 
 void

src/Charts/ChartBar.h

@@ -58,7 +58,7 @@ public slots:
     void setCurrentIndex(int index);
     void scrollLeft();
     void scrollRight();
-    void tidy();
+    void tidy(bool setwidth);
     void setChartMenu();
     void menuPopup();
     void configChanged(qint32); // appearance