Move some classes from PdmUiTreeViewEditor.cpp to the header file in order to make them available in RiuGuiTheme to adjust the style of tree views and keep the drag&drop styling.
Removed getStyleSheet function.
Added a new feature for editing style sheets and variable colors and see immediately the result.
Made Qwt plots (and items) stylable.
Added icons, improved styling possibilities of QMinimizePanel, fixed minor bugs in RicThemeColorEditorFeature.