Usually in MapViewer, when you want to invoke one of the toolbar commands, you will single-click on the toolbar button. Some of the commands take effect immediately, while other commands require further mouse action.
For example, you might click on the Zoom In toolbar button and then click on the map where you want the zoom to be centered. After the zoom, the cursor returns to the normal Select function, represented by an arrow pointer.
Sometimes you may want to repeat the command, say to zoom in again. Although you can click the button again to use it a second time, there is an easier way if you expect to use a command repeatedly.
Some of the toolbar buttons have a dual personality. You can single-click on them to invoke the command for a single use, or you can double-click on the button to use the command repeatedly. If you double-click the Zoom In button, it won't return to select mode after clicking once on the map. You can click repeatedly to zoom in further and further. To return the the normal Select mode, either click the Select toolbar button or hit the ESC key on the keyboard.
This double-click capability applies to the most of the commands on the View and Drawing toolbars, and to the Move/Resize command on the Drawing Accessories toolbar.
View toolbar commands with double-click capability
Drawing toolbar commands with double-click capability
Updated August 9, 2011