INTRO
Hello everyone in community!
I’m the Cakewalk enthusiast, which spent with Cakewalk products more than 12 years (starting with CWPA 8), and, well, I decided that I want to help make Sonar better. I spent much time analyzing, considering and testing many Sonar features, evolved with some ideas and discovered some bugs. Lately I had at last given this investigation a readable form, which resulted in many pages of review. I’d like to think that this is not just another “i want it my way” wish-list, but well-weighted and reasoned suggestions of how we can improve what we have without too much programming work from Cakewalk (because I concentrated on improving already existing features rather than demanding something totally new). Of cause it’s all based on my workflow, but I will try to discuss things that concern everyone.
Be ready for comparisons with Sonar 8.5.3, because I think there were some very useful features in it there that were cut off for no reason. There will be also some comparisons with other DAWs. I’ll try to give my considerations in logical blocks, similar to themes organization in Sonar user manual.
I engage everyone to participate in discussion and hope that guys from Cakewalk will take heed of these suggestions, maybe in Sonar X4.
P.S. Excuse me my English, I’m not a native speaker.
Let’s make Sonar better!

1.1. TRACK VIEW - COLORING.   
1.1.1. Quick track coloring in X3 is a nice addition, but, as often happens with Sonar X new features, it has side effects. In this case – Sonar became totally unsuited for “bright background” color schemes. Why? Because now we cannot change default clips background to anything than dark grey. Ok, let’s analyze this. They want to let user quickly change track color, including track header, without going to color preferences – great idea. But how it’s implemented? Instead of connecting new track color selector to corresponding option in color preferences, they fully REMOVE track background option from preferences, and now user is allowed to change only notes color, not default track clips background, which is always dark grey! As a result, we have total grayness all over the clips pane, and the only method to fight it is to deactivate “display clips content” option, that is no good. IMHO, we should see something like this in clips pane (but with more contrast between background/foreground). To make this picture, I had to tweak individually each clip’s background, because default track background colors are not available anymore.   
          
Instead, now we have something like this by default:

Which looks more appealing to you?

1.1.2. Another strange thing: selected clips by default are now shown brighter than regular, while selected track lane is shown darker than regular. Where’s logic in it? If we want selected clip to be brighter than others, let us make brighter the whole track! But thanks God, that’s still customizable.This is how selected track looks in Sonar X3:
 
And this is how it looked in Sonar 8.5.3. (“Light side” scheme):

I think this is much more easy on the eyes because selected track lane, track number and clips are all identified by dark color. track header is bright in this case, but anyway it can be custom-colored in X3
 

1.1.3. I think, the old clips coloring principle should be brought back – in clip pane, in “display clip contents” mode, depending on the track color use choose clip’s background (and not foreground (notes)!) color must vary.  Notes in clips pane may all be painted black. It’s much easier to orientate between the tracks this way, rather than where all clips are grey and only notes color vary. Maybe good solution will be to provide the option to switch this behavior in Cakewalk.ini.
Now, when “display clip contents” is deactivated, and clip headers are hidden (that is what I prefer) there is no difference in color between selected and unselected clips at all! This is not the most comfortable  way to work.
 
1.1.4 Muted clips. One of X3 “enhancements”: muted clips foreground are now dimmed, and clips no longer display a Mute icon. In fact, the mute icon was making them easily distinguishable.  Now they only differ by dimmed color, which can be sometimes misleading (with certain color schemes). They should either wear "muted" mark, or be more transparent to easily distinguish them, and background must be dimmed also, not only notes (!). Muted notes in piano roll are transparent, not just dimmed. I suggest to implement the same for clips.
 

Please, post one topic per thread and allow us to focus on it lol

Too many letters, I know) Can do it... I'm just scared of being banned for creating too many topics in a short time) You think separate topic for each number subdivision will do?

Yes, that would make it easier to follow the thread. For example, I don't use step sequencer but use linked clips a lot. Having to read each post wondering if it's the topic I'm interested in or not is tiring IMO. ;)

ОК, I'll try to differentiate topics as much as I can)  Meanwhile if you have something to say, you can do it quoting the part you're interested in

You can't change default background colors for clips, but you can change the background colors for cilps, groups of clips, or an entire track of clips using the Inspector.

Possible workaround:
 
I just exported my X3 color scehme, imported it into X2, changed the color for Tracks 1, 11, 21... Background, exported/imported the scheme to X3, and the change took for MIDI tracks 1, 11, 21.
 
So the parameter is there. It's just not exposed in X3. I've done this for other disappeared preference options in the past, both for colors and keyboard shortcuts.
 
Just be aware that importing an X2 color scheme into X3 could have other undesirable side-effects even if you start by importing X3 into X2. But you can always revert if something doesn't work out.