With default "Oxygen" colors, the color of text on the tab of a currently-not-focused konsole session is barely distinguishable. This color is computed (mixed with the normal (black) color) in TabbedViewContainer::setTabActivity() (ViewContainer.cpp#666).

It is indeed possible to configure this color (somehow, if the user knows what to search for) in the global KDE Color Schemes configuration, but it is very difficult to find out where and how to change it.

The minimum would be to provide a better default color (by not mixing with normalColor or by using e.g. NegativeText).

The best would be to change the color of the whole tab upon activity, or provide an attention-catching animation or icon in the tab.

Reproducible: Always

Steps to Reproduce:
1. Open Konsole with at least two session tabs in a KDE session with default Oxygen color scheme
2. type "sleep 3" in one session and change the focus to the other tab within 3 seconds

Actual Results:  
3. the color of the tab title text in the "sleep" tab changes to a very dark magenta, difficult to distinguish from the normal black color

Expected Results:  
fireworks ;-)