Google Apps Script – Why Isn’t the New Dashboard Available?

To @Jacob's claim of impossibility, I refute it thus... (but thanks for the improved speed)

using:

=sumIfBgColor("#ffffff", A1:A10, COLUMN(A1), ROW(A1))

with the following functions will do what you want.

/**
 * Sums cell values in a range if they have the given background color
 * 
 * @param  {String} color    Hex string of color eg ("#ffffff")
 * @param  {Array.Array} range    Values of the desired range
 * @param  {int} startcol The column of the range
 * @param  {int} startrow The first row of the range
 * 
 * @return {int}          Sum of all cell values matching the condition
 */
function sumIfBgColor(color, range, startcol, startrow){
  // convert from int to ALPHANUMERIC - thanks to 
  // Daniel at http://stackoverflow.com/a/3145054/2828136
  var col_id = String.fromCharCode(64 + startcol);
  var endrow = startrow + range.length - 1
  // build the range string, then get the background colours
  var range_string = col_id + startrow + ":" + col_id + endrow
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var getColors = ss.getRange(range_string).getBackgrounds();

  var x = 0;
  for(var i = 0; i < range.length; i++) {
    for(var j = 0; j < range[0].length; j++) {
      // Sometimes the cell background is eg 'white' rather than '#ffffff'.
      // I don't know why - I think it's a bug.
      // so we remove that inconsistency with colourNameToHex
      // courtesy of Greg at http://stackoverflow.com/a/1573141/2828136
      if(colourNameToHex(getColors[i][j].toString()) == color) {
        x += range[i][j];
      }
    }
  }
  return x;
}

/**
 * Takes a colour string and returns it to a hex string. If a non-matching string is
 * passed, it will return the argument as is - for this situation it means that a
 * hex string can be passed to it and be returned as is. This is not for production.
 * 
 * @param  {string} color    Must be either a colour name or hex string of color eg ("#ffffff")
 * 
 * @return {object|string}          hex string of color eg ("#ffffff") or the argument given.
 */
function colourNameToHex(colour)
{
    var colours = {"aliceblue":"#f0f8ff","antiquewhite":"#faebd7","aqua":"#00ffff","aquamarine":"#7fffd4","azure":"#f0ffff",
    "beige":"#f5f5dc","bisque":"#ffe4c4","black":"#000000","blanchedalmond":"#ffebcd","blue":"#0000ff","blueviolet":"#8a2be2","brown":"#a52a2a","burlywood":"#deb887",
    "cadetblue":"#5f9ea0","chartreuse":"#7fff00","chocolate":"#d2691e","coral":"#ff7f50","cornflowerblue":"#6495ed","cornsilk":"#fff8dc","crimson":"#dc143c","cyan":"#00ffff",
    "darkblue":"#00008b","darkcyan":"#008b8b","darkgoldenrod":"#b8860b","darkgray":"#a9a9a9","darkgreen":"#006400","darkkhaki":"#bdb76b","darkmagenta":"#8b008b","darkolivegreen":"#556b2f",
    "darkorange":"#ff8c00","darkorchid":"#9932cc","darkred":"#8b0000","darksalmon":"#e9967a","darkseagreen":"#8fbc8f","darkslateblue":"#483d8b","darkslategray":"#2f4f4f","darkturquoise":"#00ced1",
    "darkviolet":"#9400d3","deeppink":"#ff1493","deepskyblue":"#00bfff","dimgray":"#696969","dodgerblue":"#1e90ff",
    "firebrick":"#b22222","floralwhite":"#fffaf0","forestgreen":"#228b22","fuchsia":"#ff00ff",
    "gainsboro":"#dcdcdc","ghostwhite":"#f8f8ff","gold":"#ffd700","goldenrod":"#daa520","gray":"#808080","green":"#008000","greenyellow":"#adff2f",
    "honeydew":"#f0fff0","hotpink":"#ff69b4",
    "indianred ":"#cd5c5c","indigo ":"#4b0082","ivory":"#fffff0","khaki":"#f0e68c",
    "lavender":"#e6e6fa","lavenderblush":"#fff0f5","lawngreen":"#7cfc00","lemonchiffon":"#fffacd","lightblue":"#add8e6","lightcoral":"#f08080","lightcyan":"#e0ffff","lightgoldenrodyellow":"#fafad2",
    "lightgrey":"#d3d3d3","lightgreen":"#90ee90","lightpink":"#ffb6c1","lightsalmon":"#ffa07a","lightseagreen":"#20b2aa","lightskyblue":"#87cefa","lightslategray":"#778899","lightsteelblue":"#b0c4de",
    "lightyellow":"#ffffe0","lime":"#00ff00","limegreen":"#32cd32","linen":"#faf0e6",
    "magenta":"#ff00ff","maroon":"#800000","mediumaquamarine":"#66cdaa","mediumblue":"#0000cd","mediumorchid":"#ba55d3","mediumpurple":"#9370d8","mediumseagreen":"#3cb371","mediumslateblue":"#7b68ee",
    "mediumspringgreen":"#00fa9a","mediumturquoise":"#48d1cc","mediumvioletred":"#c71585","midnightblue":"#191970","mintcream":"#f5fffa","mistyrose":"#ffe4e1","moccasin":"#ffe4b5",
    "navajowhite":"#ffdead","navy":"#000080",
    "oldlace":"#fdf5e6","olive":"#808000","olivedrab":"#6b8e23","orange":"#ffa500","orangered":"#ff4500","orchid":"#da70d6",
    "palegoldenrod":"#eee8aa","palegreen":"#98fb98","paleturquoise":"#afeeee","palevioletred":"#d87093","papayawhip":"#ffefd5","peachpuff":"#ffdab9","peru":"#cd853f","pink":"#ffc0cb","plum":"#dda0dd","powderblue":"#b0e0e6","purple":"#800080",
    "red":"#ff0000","rosybrown":"#bc8f8f","royalblue":"#4169e1",
    "saddlebrown":"#8b4513","salmon":"#fa8072","sandybrown":"#f4a460","seagreen":"#2e8b57","seashell":"#fff5ee","sienna":"#a0522d","silver":"#c0c0c0","skyblue":"#87ceeb","slateblue":"#6a5acd","slategray":"#708090","snow":"#fffafa","springgreen":"#00ff7f","steelblue":"#4682b4",
    "tan":"#d2b48c","teal":"#008080","thistle":"#d8bfd8","tomato":"#ff6347","turquoise":"#40e0d0",
    "violet":"#ee82ee",
    "wheat":"#f5deb3","white":"#ffffff","whitesmoke":"#f5f5f5",
    "yellow":"#ffff00","yellowgreen":"#9acd32"};

    if (typeof colours[colour.toLowerCase()] != 'undefined')
        return colours[colour.toLowerCase()];

    return colour;
}

The relevant script method, as said in a comment, is

SpreadsheetApp.flush();

Which makes sure that any pending changes to the spreadsheet are actually applied before the execution continues. For example, to make sure that new data is actually entered (and not just batched, awaiting its CPU time) before the contents are emailed.

Documentation explains:

Spreadsheet operations are sometimes bundled together to improve performance, such as when doing multiple calls to Range.getValue(). However, sometimes you may want to make sure that all pending changes are made right away, for instance to show users data as a script is executing.