Warning messages are not as critical to fix as error messages; in some cases, they may be intentional (e.g. segment xyz was ignored). As such, you can toggle Warning Messages on/off at any time. If the Error/Warning pane contains both warnings and errors, only the error icon will be displayed in the associated tab.

To view a list of warnings associated with a tab, simply select the tab and a specific View (Message/Grammar/Text). The warnings are displayed in the Error/Warning pane, as shown below: