OK, since you have not posted a bug report so far, I did it for you:
https://bugs.freepascal.org/view.php?id=36399 Use it as a reference for future reports posted by yourself. In general, the link to the bug tracker is shown in the left link bar of the forum.
Adding a patch (i.e. fixing the issue yourself and submitting the difference file(s) increases the chance that a fix is accepted because the developer already gets a solution and only has to evaluate if it makes sense, is coded well etc.
Spend some time in finding a good description of the issue. Always have in mind that the developer must understand what you want to achieve and what is the issue.
To create a patch is more complex than simply writing the bug report. Firstly, you must use the development versions of Lazarus or fpc (trunk), depending on whether the issue belongs to Lazarus or FPC. Use svn to have the up-to-date sources, on Windows use the nice Explorer addon "TortoiseSVN" which is almost self-explanatory. Apply your changes to the unit(s), test everything. Finally create a patch by the svn diff command (or with TortoiseSVN right-click on the Lazarus or FPC folder, select "TortoiseSVN" > "Create patch"). Append the patch file to the bug report.
Usually it is also a good idea to add a demo project in which the developer can see the issue, and which can be used as a test after fixing it.
Find a more detailed description in the wiki:
https://wiki.freepascal.org/Creating_A_Patch