Remove unused class WidgetHider

CMakeLists.txt

@@ -613,7 +613,6 @@ add_library(mixxx-lib STATIC EXCLUDE_FROM_ALL
   src/util/timer.cpp
   src/util/valuetransformer.cpp
   src/util/version.cpp
-  src/util/widgethider.cpp
   src/util/widgetrendertimer.cpp
   src/util/workerthread.cpp
   src/util/workerthreadscheduler.cpp

build/depends.py

@@ -1317,7 +1317,6 @@ def sources(self, build):
                    "src/util/logger.cpp",
                    "src/util/logging.cpp",
                    "src/util/cmdlineargs.cpp",
-                   "src/util/widgethider.cpp",
                    "src/util/autohidpi.cpp",
                    "src/util/screensaver.cpp",
                    "src/util/indexrange.cpp",

src/preferences/dialog/dlgprefrecord.h

@@ -9,14 +9,12 @@
 #include "preferences/usersettings.h"
 #include "preferences/dlgpreferencepage.h"
 #include "encoder/encoder.h"
-#include "util/widgethider.h"
 
 class ControlObject;
 class ControlProxy;
 
 class DlgPrefRecord : public DlgPreferencePage, public Ui::DlgPrefRecordDlg  {
     Q_OBJECT
-    WidgetHider m_hider;
   public:
     DlgPrefRecord(QWidget *parent, UserSettingsPointer _config);
     virtual ~DlgPrefRecord();
@@ -39,9 +37,6 @@ class DlgPrefRecord : public DlgPreferencePage, public Ui::DlgPrefRecordDlg  {
     void apply(const QString &);
 
   private:
-    void retainSizeFor(QWidget* widget);
-    inline void showWidget(QWidget* widget);
-    inline void hideWidget(QWidget* widget);
     void setupEncoderUI();
     void loadMetaData();
     void updateTextQuality();