I think you should add some feature below, which is common on many IDEs we are using now:

• Multiple line comment/uncomment/tab (important, many IDEs have this) See : Comment and Uncomment selection using CTRL+/ Megaxela/QCodeEditor#27 and Feature request: multi-line indent using the Tab key Megaxela/QCodeEditor#18
• Multiple-file access.
• Preset and save the compiler parameter for all language (like C++, Java, Python,...) so we won't have to change it when we switch programming language.
• More themes (Monokai, Atom, etc) whatever you can add, or even better, you can add Custom Theme feature.. See Support for more themes - Monokai #60
• Indentation Coloring (wonderful for Python programmer)
• An option to set the time limit for a problem, and show up the #execution time.. On Linux your program must terminate after 5 sec of start and on windows there is no such limit. However, I have added now, the execution time is also showed.
• Detached Execution should do the trick even if we don't have system("pause") command.. This works on Linux! xterm pauses after execution however on Windows due to CMD limitations, it is not possible now! If we migrate to Powershell, this will be fixed, but due to backward compatibility we still detach on CMD.exe.