# Google preview: opacity, key & extent

Official GBMaps guide for the classic map maker. VectorMaps has a different interface.

Source: https://www.gbmaps.com/mcs/map-help.php?topic=google-controls
Updated: 2026-09-30

The preview has its own display controls. They help you read the geographic background without changing the colours or page composition of the SVG map.

![Google preview: opacity, key & extent — current GBMaps controls](https://www.gbmaps.com/mcs/help/images/google-controls.png)

Actual geographic viewer with example territories. Background © OpenStreetMap contributors. Numbers link to the explanations.

## 1. Opacity slider

Move the slider towards 0 to make the polygon fills more transparent, or towards 1 for stronger fills. A lower value lets background roads and labels show through. It changes the preview overlay’s fill opacity, not the saved print-map colours.

[Open this step](https://www.gbmaps.com/mcs/map-help.php?topic=google-controls#google-controls--opacity)

## 2. Reset the geographic view

The target-style reset control returns to the viewer’s overview extent. It is separate from Fit map in the artwork editor. Use it when you have panned away from the area you meant to inspect.

[Open this step](https://www.gbmaps.com/mcs/map-help.php?topic=google-controls#google-controls--reset)

## 3. The preview key

Shows territory colours, names and enabled extra legend text. Hold and drag this key to move it clear of an important part of the geographic map. Its entries are for reference: they do not select a territory for painting or reorder the SVG key. Unlike the portrait SVG key, this viewer key has no dedicated wheel-resize control.

[Open this step](https://www.gbmaps.com/mcs/map-help.php?topic=google-controls#google-controls--key)

## 4. Assigned polygons only

Hide unassigned areas carries through to this polygon overlay. The base map remains visible outside the coloured territories. If you see roads or place names there, those can be part of the background rather than unassigned postcode polygons.

[Open this step](https://www.gbmaps.com/mcs/map-help.php?topic=google-controls#google-controls--focus)

## 5. Opening a geographic view from saved files

Open the Google/view link for the saved map. New views are private to your account until you choose Share this view and confirm that anyone with the link may see the map and its labels. Copy public link gives you the viewing address; it does not let another person edit your map or open your account. Stop sharing switches off the public link and any embeds using it. Existing published links continue to work until their owner stops sharing them.

[Open this step](https://www.gbmaps.com/mcs/map-help.php?topic=google-controls#google-controls--sharing)

## 6. Move the preview key

Drag the key with the mouse or a single finger to place it away from the geography you are inspecting. The movement belongs to this viewer. To place the key for a PDF, return to the editor and move the SVG key there.

[Open this step](https://www.gbmaps.com/mcs/map-help.php?topic=google-controls#google-controls--key-drag)

## Related guides

- [On Google: explore the geographic preview](https://www.gbmaps.com/mcs/map-help.php?topic=google)
- [Show only your assigned territories](https://www.gbmaps.com/mcs/map-help.php?topic=hide-unassigned)
- [Find, reopen & manage saved files](https://www.gbmaps.com/mcs/map-help.php?topic=saved-files)
- [On Google: labels inside ZIP and county areas](https://www.gbmaps.com/mcs/map-help.php?topic=google-labels)
- [Share an On Google map for two hours](https://www.gbmaps.com/mcs/map-help.php?topic=google-temporary-share)