+ Neither X/Open Curses nor the SVr4 manual pages give details about the
+ way the rendition of characters on the screen is updated when <STRONG>bkgd</STRONG> or
+ <STRONG>wbkgd</STRONG> is used to change the background character.
+
+ This implementation, like SVr4 curses, does not store the background
+ and window attribute contributions to each cell separately. It updates
+ the rendition by comparing the character, non-color attributes and col-
+ ors contained in the background. For each cell in the window, whether
+ or not it is blank:
+
+ <STRONG>o</STRONG> The library first compares the <EM>character</EM>, and if it matches the
+ current character part of the background, it replaces that with the
+ new background character.
+
+ <STRONG>o</STRONG> The library then checks if the cell uses color, i.e., its color
+ pair value is nonzero. If not, it simply replaces the attributes
+ and color pair in the cell with those from the new background char-
+ acter.
+
+ <STRONG>o</STRONG> If the cell uses color, and that matches the color in the current
+ background, the library removes attributes which may have come from
+ the current background and adds attributes from the new background.
+ It finishes by setting the cell to use the color from the new back-
+ ground.
+
+ <STRONG>o</STRONG> If the cell uses color, and that does not match the color in the
+ current background, the library updates only the non-color
+ attributes, first removing those which may have come from the cur-
+ rent background, and then adding attributes from the new back-
+ ground.
+