The level of semantic auditing affects which messages AutoCAD issues for a DCL file (see Semantic Auditing of DCL Files). For example, the hidedcl dialog box defined in Functions for Hiding Dialog Boxes is displayed without any warnings, if you use the default audit level. If you set the audit level to 3, though, AutoCAD displays an alert dialog box with a warning message. You can see this for yourself by inserting the following line at the beginning of hidedcl:
dcl_settings : default_dcl_settings { audit_level = 3; }
Try using the VLISP DCL Preview feature to view the dialog box defined in hidedcl. You will be alerted to view the acad.dce file, which contains the following messages:
=== DCL semantic audit of C:/PROGRA~1/AUTOCA~1/VLISP/$vld$.dcl ===
Hint in "hidedcl". (widget type = text, key = "message")
fixed_height = true is probably redundant.
At lower (less discriminating) levels of semantic auditing, AutoCAD does not look for redundant attribute definitions and the dialog box displays normally.
Remove the fixed_height = true statement from the DCL to correct the situation AutoCAD is warning you about.