I created an interactive report having 35 columns in output. In that, value of the column / filed number 3 can be 1 to 4000 (min 1 and max 4000 characters) characters per record.
So I want to show maximum of first 30 characters per record in the output initially. When mouse over in the field 3, it has to show full data in an overlap popup.
Please suggest if this can be possible in Apex 4.2
Your requirement look similar to the one posted in this thread: APEX Interactive Report OnMouseOver Row
So, you can follow Jari's answer (might need some customization in your case).
Otherwise, Apex 4.2 comes with a number of packaged applications like Decision Maker, P-Track*** etc. If you look at their Home page, they have regions built using "PL/SQL Dynamic Content". If you place the mouse over the records in the regions, you will notice a pop-up window with the help content for that record. The list is built using the "detailedStatusList" class and then, the list entries (detailed tool tip) using "detailedListTooltip" class. Finally, they call "detailedStatusListToolTip();" function when the page loads. You can also explore this option as the pop-up comes with a nice UI.