selected = "selected" to better fit the xml
fixed undefined variable $is_display for method  _getCheckBoxesForMultipleRowOperations
correct test for getCheckBoxesForMultipleRowOperations
correct test for getCheckBoxesForMultipleRowOperations / part 2
Merge pull request #143 from Gemorroj/master

fixed undefined variable $is_display for method _getCheckBoxesForMultipleRowOperations
Show error messages when unable to display chart
Revert "remove unused variables"

This reverts commit cb9e34d42a36c98835454f9181eabf593889654e.

-> $error_header, $lang and $dir are used in the included file
libraries/error.inc.php
add comment why variables are still needed
Merge pull request #145 from zixtor/master

When unable to display chart, show appropriate error message.
Coding style improvements
fix bug #3783, instanciate class before calling static method
Throw error if no sql query is set
Merge pull request #146 from ruleant/bug_3783

fix bug #3783, instanciate class before calling static method
Fixed XSS in "change column" functionality