There are a few scenarios in which Sonar leaves an empty take lane or lanes without your knowledge (if you normally work with lanes collapsed). The below test shows one of them.
 
1. Create a new project.
2. Drag a long, audio or MIDI file (more than 7 bar-long in this test) from the Browser into the Track view's Clips pane, at the start of bar 1. (Let's use an audio file called "DBD_175_A_MUSIC_LP5" in Audio Library->Loops->Loopmasters->BREAKS DRUM N BASS->DANNY BYRD)
3. Hold CTRL and drag the clip to the start of the next bar (to make the clips overlapped). Repeat this 4 times.
4. Click the Expand/Collapse Take Lanes button in the track header to expand the lanes. Your Track view should now look like this:

 
5. Hit CTRL+Z (undo) until you see only the original clip.
 
[Expected Result]
Lanes 2-6 (T2-T6) are automatically deleted by the undo's.
 
[Actual Result]
Lanes 2-6 are still there, wasting precious screen space, like this:

 
 
Issue #: CWBRN-23897
Reported on Feb 4, 2014
Confirmed and submitted to development on Feb 5, 2014
 
 
 

I'm not sure deleting the lanes would be the expected result. If you delete clips in a track, the track remains. Take Lanes, which have much in common with tracks, probably follow the same protocol so that's how I would expect them to react. Whether that's the most desirable way to react is a different matter.
 
I believe that implementing what you want would require that Take Lanes have a different underlying architecture compared to Tracks. You wouldn't want tracks to go away if you deleted all the clips within it, as you may have FX bin and ProChannel settings you want to retain as you overdub a new clip. However Take Lanes don't have FX bins and ProChannel settings, so if you deleted the Lane with the clips, the only characteristic you would lose is the solo/mute/record status - which would be irrelevant anyway.

Craig, it's not delete I performed in the above steps. It's undo. Undo means to cancel the previous action, no?

Can repro. Yup undo isn't fully undo'ing...

Jlien X
Craig, it's not delete I performed in the above steps. It's undo. Undo means to cancel the previous action, no?

 
Ah, now I see what you're saying. I'm reading through things fast because I'm deleting zillions of spam messages and it has me pretty frazzled.

It looks like SONAR remembers the number of lanes even when the track itself is "Undone":
Drag some audio to empty space, so new track is created. Than the same as in the original
example (several lanes). Than "Undo" the whole procedure, till the track is removed.
Then "Redo": the new track is created again with many empty lanes.
But common, killing lane is on click action

According to Jlien X not fixed in X3E.

Jlien X
There are a few scenarios in which Sonar leaves an empty take lane or lanes without your knowledge (if you normally work with lanes collapsed). The below test shows one of them.
 
1. Create a new project.
2. Drag a long, audio or MIDI file (more than 7 bar-long in this test) from the Browser into the Track view's Clips pane, at the start of bar 1. (Let's use an audio file called "DBD_175_A_MUSIC_LP5" in Audio Library->Loops->Loopmasters->BREAKS DRUM N BASS->DANNY BYRD)
3. Hold CTRL and drag the clip to the start of the next bar (to make the clips overlapped). Repeat this 4 times.
4. Click the Expand/Collapse Take Lanes button in the track header to expand the lanes. Your Track view should now look like this:

 
5. Hit CTRL+Z (undo) until you see only the original clip.
 
[Expected Result]
Lanes 2-6 (T2-T6) are automatically deleted by the undo's.
 
[Actual Result]
Lanes 2-6 are still there, wasting precious screen space, like this:

 
 
Issue #: CWBRN-23897
Reported on Feb 4, 2014
Confirmed and submitted to development on Feb 5, 2014
 
 
 

What I fins strange is that you have 6 take lanes with track info and you move every track up 1 bar then the undo Ctrl+Z should just undo the 1 bar move and not delete the whole track.

Well, I didn't "move" the clips, I duplicated them from the original clip, that's why the undo made the clips disappear. The issue here is that the lanes are still displayed, and you have to manually delete them (one by one or by using the "Remove empty lanes" command). I wish Take Lanes had an auto-empty-lane-removal feature.

Jlien X
I wish Take Lanes had an auto-empty-lane-removal feature.

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http://www.cakewalk.com/Documentation/default.aspx?Doc=SONAR%20X3&Lang=EN&Req=Arranging.49.html