cell-horizontal-border-color

Arguments: grid-row grid-column

The line that is drawn as a border between two grid-rows of a grid-widget is typically drawn in a single color from the left side of the whole grid to the right side. If it is desirable instead to draw the line in different colors where it crosses particular grid-columns, then an application can supply cell-horizontal-border-color methods to specify these colors. An application could also call this function, though there is probably no need to do so.

This generic function is called internally when drawing the cell at the intersection of grid-row and grid-column, to see if the border along the bottom of the cell should be drawn in a different color than the general color of that border (which is returned by effective-border-color). The method may return either an RGB color object in order to use that color (see make-rgb), or nil to default to the border's general color, or t to use the cell's effective-background-color. The default method returns nil.

The special value of t (to draw the border with the cell's background color) will effectively remove the border from the bottom of the cell. This may be useful for making two contiguous cells appear as a single cell (though they will still behave as separate cells when moving the keyboard focus, for example). If it is desired to draw a single picture in the interior of the combined cells, then any graphic that lies across the border between the cells should be drawn in the draw-cell method for each of the cells; this will ensure that the graphic is drawn whenever needed. The employee grid example on the Examples tab of the Navigator dialog contains a fancy example of this, to cover a few tricky small aspects of this advanced technique.

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This page was not revised from the 10.0 page.
Created 2019.8.20.