[kstyle]: Give active document tabs a thick highlight

BUG: 356037

kstyle/breezehelper.cpp

@@ -1294,8 +1294,11 @@ namespace Breeze
     }
 
     //______________________________________________________________________________
-    void Helper::renderTabBarTab( QPainter* painter, const QRect& rect, const QColor& color, const QColor& outline, Corners corners ) const
-    {
+    void Helper::renderTabBarTab(QPainter *painter, const QRect &rect,
+                                const QColor &color, const QColor &highlight,
+                                const QColor &outline, Corners corners,
+                                bool document, bool bottom) const {
+
 
         // setup painter
         painter->setRenderHint( QPainter::Antialiasing, true );
@@ -1322,6 +1325,22 @@ namespace Breeze
         QPainterPath path( roundedPath( frameRect, corners, radius ) );
         painter->drawPath( path );
 
+        if (highlight.isValid() && document) {
+            auto rect = frameRect;
+            rect.setHeight(2);
+            if (bottom) {
+                rect.setTop(frameRect.bottom()-2);
+                rect.setBottom(frameRect.bottom());
+            }
+
+            QPainterPath rectAsPath;
+            rectAsPath.addRect(rect);
+
+            painter->setClipPath(path.intersected(rectAsPath));
+            painter->setBrush(highlight);
+            painter->drawRect(frameRect);
+        }
+
     }
 
     //______________________________________________________________________________

kstyle/breezehelper.h

@@ -240,7 +240,10 @@ namespace Breeze
         void renderScrollBarBorder( QPainter*, const QRect&, const QColor& ) const;
 
         //* tabbar tab
-        void renderTabBarTab( QPainter*, const QRect&, const QColor& color, const QColor& outline, Corners ) const;
+        void renderTabBarTab( QPainter*, const QRect&, const QColor& color, const QColor& highlight, const QColor& outline, Corners, bool document, bool bottom ) const;
+        // TODO(janet): document should be set based on whether or not we consider the
+        // tab user-editable, but Qt apps often misuse or don't use documentMode property
+        // so we're currently just always setting it to true for now
 
         //* generic arrow
         void renderArrow( QPainter*, const QRect&, const QColor&, ArrowOrientation ) const;

kstyle/breezestyle.cpp

@@ -5707,6 +5707,8 @@ namespace Breeze
         // for QtQuickControls, ovelap is already accounted of in the option. Unlike in the qwidget case
         const int overlap( isQtQuickControl ? 0:Metrics::TabBar_TabOverlap );
 
+        bool bottom = false;
+
         // adjust rect and define corners based on tabbar orientation
         Corners corners;
         switch( tabOption->shape )
@@ -5738,6 +5740,7 @@ namespace Breeze
 
                 corners = CornerBottomLeft|CornerBottomRight;
                 rect.adjust( 0, - 1, 0, 0 );
+                bottom = true;
 
             } else {
 
@@ -5820,18 +5823,24 @@ namespace Breeze
         // outline
         const auto outline( selected ? _helper->alphaColor( palette.color( QPalette::WindowText ), 0.25 ) : QColor() );
 
+        QColor accent;
+        if ( selected )
+        {
+            accent = palette.color( QPalette::Active, QPalette::Highlight );
+        }
+
         // render
         if( selected )
         {
 
             QRegion oldRegion( painter->clipRegion() );
             painter->setClipRect( option->rect, Qt::IntersectClip );
-            _helper->renderTabBarTab( painter, rect, color, outline, corners );
+            _helper->renderTabBarTab( painter, rect, color, accent, outline, corners, true, bottom );
             painter->setClipRegion( oldRegion );
 
         } else {
 
-            _helper->renderTabBarTab( painter, rect, color, outline, corners );
+            _helper->renderTabBarTab( painter, rect, color, accent, outline, corners, true, bottom );
 
         }