By default, WinCatalog shows thumbnails on a white background. That works for most images, but it’s a poor match for transparent PNGs, logos, and icons, where a white shape can vanish into the page. You can pick a different background color for the thumbnail preview panel, and have the same color used in the Thumbnails List View.

Changing the preview-panel background

The thumbnail preview panel is the pane on the right that shows a large preview of the selected item.

1. Move the mouse over the thumbnail preview panel. A small band of color swatches appears near the caption.
2. Click a swatch to apply that background color right away:
   • Default (white)
   • Dark Grey
   • Light Grey
   • Red
   • Blue

The swatches fade when the mouse leaves the panel and come back when you hover over it again, so they don’t get in the way. WinCatalog remembers your choice.

You can also right-click the preview panel for its menu, which has Change background and a Stretch thumbnails toggle. Stretch makes the image fill the panel instead of showing it at native size.

Applying the color to the Thumbnails List View

By default, the color you pick also applies to the tiles in the Thumbnails List View, so the main view matches the preview panel. The control background (the gaps between tiles and the label area) stays neutral so labels remain easy to read. Only the tile behind each thumbnail takes the color.

If you’d rather keep the Thumbnails List View on the standard system background no matter which swatch you pick, there’s an option for that (on by default). Turn it off to keep the list view separate from the preview-panel color.

Tip: A neutral grey is a safe choice for a mixed collection, since it keeps both light and dark transparent images readable.