When someone sends text that has the same colour as the background of the terminal, or has the same background and foreground colour specified (ex: <ctrl+c color code flag>1,1black text on black background) Konsole fails to show the text on highlight, instead just showing a black box.

Reproducible: Always

Steps to Reproduce:
1.  Open an IRC client in Konsole, send text using a colour code (ctrl+c, then type 1,1 on irssi for example)
2. Highlight the text
3. Text is still unreadable on highlight
Actual Results:  
Konsole highlights and copies the text, but it is still unreadable.

Expected Results:  
Konsole shows the text on highlight, preferably white on black or black on white depending on colour theme.  For expected results, try out urxvt.

Workaround involves highlighting the text to copy it to the X buffer, and then middle click pasting it into a text editor.  A hassle, but works.