Selection highlights are shown on the contour and/or surface of selected elements.
Element information highlights are used to assist in selection (pre-selection highlight) and identifying related elements e.g. for labels and dimensions (related elements highlight).
All these highlights can be configured in Options > Work Environment > Selection and Element Information, or you can turn off selection highlights altogether.
Even if you leave the Selection Highlight function on, you may want to disable it temporarily – for example, if you want to see the actual display colors of lines and fills. To suspend Selection highlight, use the Ctrl/Alt + spacebar shortcut.
Note: Surface highlights in 3D are available only when using the OpenGL 3D engine.
The pre-selection highlight appears when you hover the cursor over a selectable element, then press Shift.
Note: If the Arrow tool is active, the highlight appears on its own, without your having to press Shift.
When working in 3D, you will notice that the informational highlight acts on the entire outline of the element: even hidden lines of its contour are shown. Grouped elements are highlighted individually.
During dimensioning, labeling, and Door/Window placement, the contours of related elements will be highlighted to help you identify which element you are working on.
The related elements highlight also works with the Parameter transfer functions (Pick Up Parameters and Inject Parameters commands): the information highlight appears along with the eyedropper/syringe cursors right before you complete the parameter transfer. You do not need to press Shift to see the related elements highlight when using the Parameter Transfer function.
To choose one of several overlapping elements, hover over the elements, then press Tab to cycle the highlight among the elements.
When you are satisfied that the appropriate element is highlighted, click with the cursor to select or edit it.
In the following image, the related elements highlight and Info Tag tell you that the linear dimension you are placing will be associated to the highlighted column, not to the wall.
If you’d rather associate the dimension to the wall, click the Tab key until the wall is highlighted, then place the dimension.