Version:           1.3.1 (using KDE 4.6.5) 
OS:                Linux

Insufficient checks on a number of characters in the input line can lead to posting more then 4 kB of characters to IRC channel without any warning about size of post. 

Reproducible: Always

Steps to Reproduce:
Enter in input line large number of spaces and press Enter. 

Actual Results:  
Line is posted, spamming channel and making few "friends" along the way. 

Expected Results:  
Warning that size of posting is too large and giving chance to discard the line. 

I tested this with long string of blank spaces and with string starting with large number of spaces, which is what happened by accident when space bar was pressed, cursor run out of visible part of the input line, and when Enter was pressed all blanks were posted.