b900f425fc9e8969ff68a2fc3b327eb215000e84
galt
  Wed Dec 9 20:23:36 2015 -0800
fixing 12242 comment 92 part 2. If guidelines are turned off, the 'Highlighting alternating regions' doesn't work ( reported by kate )

diff --git src/hg/hgTracks/hgTracks.c src/hg/hgTracks/hgTracks.c
index 3bfe87b..fbff0e1 100644
--- src/hg/hgTracks/hgTracks.c
+++ src/hg/hgTracks/hgTracks.c
@@ -5025,30 +5025,34 @@
 			y, ynew, flatTrack->maxHeight);
 		    }
 		}
             }
         }
     }
 else
     {
     leftLabelX = leftLabelWidth = 0;
     }
 
 
 /* Draw guidelines. */
 if (galtDebug)
 warn("Draw guidelines");  // OR window separators in virtMode multi-window mode
+
+if (virtMode && emAltHighlight)
+    withGuidelines = TRUE;  // we cannot draw the alternating backgrounds without guidelines layer
+
 if (withGuidelines)
     {
     struct hvGfx *bgImg = hvg; // Default to the one image
     boolean exists = FALSE;
     if (theImgBox)
         {
         struct tempName gifBg;
         char base[64];
 	if (virtMode) // window separators
 	    {
 	    safecpy(base,sizeof(base),"winSeparators");  // non-reusable temp file 
 	    trashDirFile(&gifBg, "hgt", base, ".png");
 	    exists = FALSE;
 	    }
 	else  // re-usable guidelines
@@ -5069,37 +5073,34 @@
 
     if (!exists)
         {
 
         hvGfxSetClip(bgImg, fullInsideX, 0, fullInsideWidth, pixHeight);
         y = gfxBorder;
 
 	if (virtMode)
 	    {
 	    // vertical windows separators
 
 	    if (emAltHighlight)
 		{
 		// light blue alternating backgrounds
 		Color lightBlue = hvGfxFindRgb(bgImg, &guidelineColor);
-		//boolean blueBack = FALSE;
 		for (window=windows; window; window=window->next) // background under every other window
 		    {
-		    //if (blueBack)
 		    if (window->regionOdd)
 			hvGfxBox(bgImg, window->insideX, 0, window->insideWidth, pixHeight, lightBlue);
-		    //blueBack = !blueBack;
 		    }
 		}
 	    else
 		{
 		// red vertical lines
 		Color lightRed = hvGfxFindRgb(bgImg, &vertWindowSeparatorColor);
 		for (window=windows->next; window; window=window->next) // skip first window, not needed
 		    hvGfxBox(bgImg, window->insideX, 0, 1, pixHeight, lightRed);
 		}
 	    }
 	else
 	    {
 	    int x;
 	    Color lightBlue = hvGfxFindRgb(bgImg, &guidelineColor);
 	    for (x = fullInsideX+guidelineSpacing-1; x<pixWidth; x += guidelineSpacing)