Version 4.0 was improved on the following points:
1) Color transformation was sped up by using integer arithmetic and Int32Array parameters for the low level transform.
2) The use of the element computed styles was eliminated for reasons of speed.
3) Image content is now reloaded when necessary and replaced by either canvas background elements or data URLs.
4) Large images are now transformed asynchronously by a separate web worker to make the page update faster.
5) List-style-images are now included with the foreground styles and their image references are replaced by data URLs.
6) The global ColorTransform style rules are now inserted in a new style sheet and no more in the first available style sheet.
7) Color attributes are now replaced by inline styles on body, table, tbody, tr, td and font elements only.
8) Stored coefficients are placed in a single char pref instead of four different ones.
9) The minimum Firefox version was set to 17.0 because it is the first version with sufficiently high quality memory management.
10)Two options were added for the inclusion of iframes and child elements.
11)One option was added to switch between strongly and weakly blending of theme colors with page colors.
12)One option was added to switch between large and small steps for the 18 HSL component transforms.
13)Three options were added for the exclusion of large images, for scaling images down, and for changing the hue of images only.
14)One option was added to restore the default settings including the transform.
15)Six more themes were added and the readability of the themes was improved.
16)The 16 HSLC transforms were replaced by 18 HSL transforms (contrast was merged and two functions were added for hue and saturation).
17)Code was added to transform html documents automatically when they are loaded, with separate options for iframes.
18)Clicking the main button now toggles automatic transformation (single click) or applies the saved transformation (double-click).
19)The use of getMostRecentWindow was prevented throughout the extension by obtaining direct references to XUL documents from events.
20)The popup menu/panel is now aligned at the right side with the button to prevent it to be hidden beneath an os bar at the right.
21)The default color transform is empty now, as this makes more sense for the 'Restore defaults' option.
22)Stylesheet children of CSSImportRules are now included in the recursive modification of styles (bug fix).
23)Color names in background-image styles are now replaced within 'gradient*)'-sub-strings only (bug fix).
24)For safety and speed, images are no more replaced with canvas elements but are made transparent with canvas backgrounds (bug fix).
25)The ColorTransform element focus now responds correctly to scrolling and zooming and it is no more color-transformed (bug fix).
26)Background colors for document.body and document.documentElement are correctly combined now (bug fix).
27)The menu is now correctly changed in all browsers at once (bug fix).