Displays a grid of vertical and horizontal lines inside the panel, drawn 1 pixel wide with the grid color. The lines start from the center point and are spaced according to grid x step, grid y step (and grid z step on 3D panels), so they follow the zoom factor and the center position settings. The rulers (see show vertical ruler and show horizontal ruler) put their graduations on the same line positions, even when the grid itself is hidden.

Color of the grid lines. When the panel quick color is changed, it takes the grid color of the current color set.
Gap between two grid lines along the X axis of the panel space, as a fraction of the panel working width: 0.1 (default) gives 10 divisions across the panel at zoom factor 1. Range 0.01 to 1. The gap in pixels is multiplied by the zoom factor and doubled as many times as needed to stay above min grid space. The X axis is horizontal in the top view (and on 2D panels) as well as in the front and rear views.
Gap between two grid lines along the Y axis of the panel space, as a fraction of the panel working height: 0.1 (default) gives 10 divisions at zoom factor 1. Range 0.01 to 1, same zoom and min grid space behavior as grid x step. The Y axis is vertical in the top view (and on 2D panels) and horizontal in the side views.
Gap between two grid lines along the Z axis of the panel space, as a fraction of the panel working height (default 0.1, range 0.01 to 1). Only available on 3D panels: the Z axis is drawn vertically in the side, front and rear views of the view 3D setting, and is not visible in the top view.
Minimum distance in pixels between two grid lines, from 0 to 100 (default 10). When the zoom factor or the panel size brings the lines closer than this value, the step is doubled until the lines are far enough apart, which avoids a too dense grid when zooming out. It applies to the ruler graduations as well.
Position of the center point along the X axis of the panel space, from 0 to 1 (default 0.5 = middle of the panel). The center point is the origin of the grid, of the ruler graduations, of the center circle and of the axis. The offset from the middle is scaled by the zoom factor and combined with the zoom center.
Position of the center point along the Y axis of the panel space, from 0 to 1 (default 0.5 = middle of the panel): vertical position in the top view (and on 2D panels), horizontal position in the side views.
Position of the center point along the Z axis of the panel space, from 0 to 1 (default 0.5). Only available on 3D panels; it moves the center vertically in the side, front and rear views and has no visible effect in the top view.
Draws a filled disc at the center point, with the center point color and the center point size.

Color of the center point. When the panel quick color is changed, it becomes the complementary color of the panel color.
Radius of the center point in pixels, from 0 to 100 (3 pixels when the panel is created): the disc diameter is twice this value. The size does not change with the zoom factor.
Draws an outlined circle (not filled) around the center point, with the center circle diameter, center circle color and center circle line width.

Diameter of the center circle as a fraction of the smallest dimension of the panel (width or height), from 0 to 1: 0.1 (default) draws a circle 10% of the panel size, 1 draws a circle as large as the panel. The diameter is multiplied by the zoom factor.
Color of the circle line. When the panel quick color is changed, it becomes a lighter version of the center point color.
Thickness of the circle line in pixels, from 1 to 10 (default 1).
Draws the three axis of the 3D space starting from the center point: X in red, Y in green and Z in blue, with a 2-pixel line. Only available on 3D panels. The two axis lying in the plane of the current view 3D (top, side, front or rear) are always drawn; the third one, perpendicular to the screen, is drawn only when show orthogonal axis is ON.

Length of the axis lines as a fraction of the largest dimension of the panel (width or height), from 0 to 1 (default 0.2), multiplied by the zoom factor.
Opacity of the axis lines, from 0 (invisible) to 1 (opaque), default 0.5. It is combined with the general opacity of the panel.
When ON, the axis perpendicular to the current view (the one pointing into the screen, for example Z in the top view or X in the side views) is also drawn, as a diagonal line at 45 degrees starting from the center point. When OFF, only the two axis of the view plane are visible.

Inverts the direction of the Y axis in the display: when OFF, the Y ruler graduations increase from top to bottom (in the top view) and the green Y axis points downward; when ON, the graduations increase from bottom to top and the Y axis points upward. In the side views, where Y is horizontal, the horizontal graduations are inverted the same way. Only available on 3D panels; it changes the way the rulers and axis are drawn, not the values of the module.

version 7.0.250121
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