Themes: Enable using the original Window color for toolbars

This patch adds a flag which enables the "fancy" side/tool/status bars
to use the original Window color from the application palette.

The flag is disabled for all themes by default.

Task-number: QTCREATORBUG-16331
Change-Id: I1433e865e1903012d521a2cdb7083f110086e455
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@theqtcompany.com>

share/qtcreator/themes/dark.creatortheme

@@ -216,6 +216,7 @@ FlatSideBarIcons=true
 FlatProjectsMode=true
 FlatMenuBar=true
 ToolBarIconShadow=true
+WindowColorAsBase=false
 
 [Gradients]
 DetailsWidgetHeaderGradient\1\color=0

share/qtcreator/themes/default.creatortheme

@@ -187,6 +187,7 @@ FlatSideBarIcons=false
 FlatProjectsMode=false
 FlatMenuBar=false
 ToolBarIconShadow=true
+WindowColorAsBase=false
 
 [Gradients]
 DetailsWidgetHeaderGradient\1\color=ffffff

share/qtcreator/themes/flat-dark.creatortheme

@@ -221,6 +221,7 @@ FlatSideBarIcons=true
 FlatProjectsMode=true
 FlatMenuBar=true
 ToolBarIconShadow=true
+WindowColorAsBase=false
 
 [Gradients]
 DetailsWidgetHeaderGradient\1\color=0

share/qtcreator/themes/flat-light.creatortheme

@@ -198,6 +198,7 @@ FlatSideBarIcons=true
 FlatProjectsMode=false
 FlatMenuBar=false
 ToolBarIconShadow=false
+WindowColorAsBase=false
 
 [Gradients]
 DetailsWidgetHeaderGradient\1\color=0

share/qtcreator/themes/flat.creatortheme

@@ -197,6 +197,7 @@ FlatSideBarIcons=true
 FlatProjectsMode=false
 FlatMenuBar=false
 ToolBarIconShadow=true
+WindowColorAsBase=false
 
 [Gradients]
 DetailsWidgetHeaderGradient\1\color=0

src/libs/utils/stylehelper.cpp

@@ -114,6 +114,12 @@ QColor StyleHelper::m_requestedBaseColor;
 
 QColor StyleHelper::baseColor(bool lightColored)
 {
+    static const bool windowColorAsBase = creatorTheme()->flag(Theme::WindowColorAsBase);
+    if (windowColorAsBase) {
+        static const QColor windowColor = QApplication::palette().color(QPalette::Window);
+        return windowColor;
+    }
+
     if (!lightColored)
         return m_baseColor;
     else

src/libs/utils/theme/theme.h

@@ -326,7 +326,8 @@ public:
         FlatSideBarIcons,
         FlatProjectsMode,
         FlatMenuBar,
-        ToolBarIconShadow
+        ToolBarIconShadow,
+        WindowColorAsBase
     };
 
     bool flag(Flag f) const;