Another possibility may be to use vector icons in toolbar. Something to try may be to include an icon font file FontAwesome in the application, and use its glyphs, by making a text toolbar button with the font set to the icon font.
New version 1.1.5 of FolderSize tool is released.
CHG: FolderSize example: Updated Options dialog screenshot.
CHG: FolderSize example: Fixed typo in comment.
CHG: FolderSize example: Hide the "Show in Explorer context menu" button when publishing Windows Store application.
CHG: FolderSize example: Updated version to 1.1.5 in preparation for release.
CHG: FolderSize example: Optimized the file icons image list to avoid adding duplicate icons to it.
CHG: FolderSize example: Added setting whether to show file icons.