ChannelTabControl not handling channel closing correctly

Right now after closing a currently active channel, ChannelTabControl always switches to the channel on its left (the previous one). However, as indicated by the comments in the code, the desired behavior would be for it to always switch to the next one (on its right side), only exception being if it was the last channel on the list.

This is also mentioned by ppy/osu-framework#3152, though as I’m not experienced enough to investigate this issue framework-wise, I wanted to focus on this specific scenario here.

This problem seems to be caused by conflicting RemoveChannel and tabCloseRequested functions.

tabCloseRequested seems to launch first after closing a channel, switching the tab if the closed one was currently active. However, TabContainer.IndexOf(tab) returns the index counting from the right side of the channel list, making the tab selecting part underneath work incorrectly (it assumes counting from the left):

if (tab == SelectedTab && totalTabs > 1)
     // Select the tab after tab-to-be-removed's index, or the tab before if current == last
     SelectTab(TabContainer[currentIndex == totalTabs ? currentIndex - 1 : currentIndex + 1]);

After this, RemoveChannel’s Current.Value == channel check is never gonna be true due to tabCloseRequested changing the tab beforehand. Even if it did execute, it seems to only set the Current value instead of using SelectTab(), so it seems kinda obsolete.

I can fix this, but I’m not sure which of these functions is desired to handle the switching and if the order of items being reversed (as indicated by the IndexOf call) is intended.

[thewildtree]

Thanks, that makes a lot more sense. I’ll make a PR in a minute.

[thewildtree]

Closed by #8270.