Add wxActivityIndicator control.

This is a simple animated control indicating some program activity.

Provide native GTK+ (for > 2.20) and OS X implementations as well as a generic
one used under MSW.

Update the sample and the documentation.

configure

@@ -1242,6 +1242,7 @@ enable_dnd
 enable_controls
 enable_markup
 enable_accel
+enable_actindicator
 enable_addremovectrl
 enable_animatectrl
 enable_bannerwindow
@@ -2174,6 +2175,7 @@ Optional Features:
   --disable-controls      disable compilation of all standard controls
   --enable-markup         support wxControl::SetLabelMarkup
   --enable-accel          use accelerators
+  --enable-actindicator   use wxActivityIndicator class
   --enable-addremovectrl  use wxAddRemoveCtrl
   --enable-animatectrl    use wxAnimationCtrl class
   --enable-bannerwindow   use wxBannerWindow class
@@ -11245,6 +11247,50 @@ fi
 $as_echo "$result" >&6; }
 
 
+          enablestring=
+          defaultval=$wxUSE_ALL_FEATURES
+          if test -z "$defaultval"; then
+              if test x"$enablestring" = xdisable; then
+                  defaultval=yes
+              else
+                  defaultval=no
+              fi
+          fi
+
+          { $as_echo "$as_me:${as_lineno-$LINENO}: checking for --${enablestring:-enable}-actindicator" >&5
+$as_echo_n "checking for --${enablestring:-enable}-actindicator... " >&6; }
+          # Check whether --enable-actindicator was given.
+if test "${enable_actindicator+set}" = set; then :
+  enableval=$enable_actindicator;
+                          if test "$enableval" = yes; then
+                            wx_cv_use_actindicator='wxUSE_ACTIVITYINDICATOR=yes'
+                          else
+                            wx_cv_use_actindicator='wxUSE_ACTIVITYINDICATOR=no'
+                          fi
+
+else
+
+                          wx_cv_use_actindicator='wxUSE_ACTIVITYINDICATOR=${'DEFAULT_wxUSE_ACTIVITYINDICATOR":-$defaultval}"
+
+fi
+
+
+          eval "$wx_cv_use_actindicator"
+
+          if test x"$enablestring" = xdisable; then
+            if test $wxUSE_ACTIVITYINDICATOR = no; then
+              result=yes
+            else
+              result=no
+            fi
+          else
+            result=$wxUSE_ACTIVITYINDICATOR
+          fi
+
+          { $as_echo "$as_me:${as_lineno-$LINENO}: result: $result" >&5
+$as_echo "$result" >&6; }
+
+
           enablestring=
           defaultval=$wxUSE_ALL_FEATURES
           if test -z "$defaultval"; then
@@ -23706,7 +23752,7 @@ if ac_fn_c_try_link "$LINENO"; then :
           echo "*** you may also be able to get things to work by modifying LD_LIBRARY_PATH"
 else
    echo "*** The test program failed to compile or link. See the file config.log for the"
-          echo "*** exact error that occured. This usually means GTK+ is incorrectly installed."
+          echo "*** exact error that occurred. This usually means GTK+ is incorrectly installed."
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
@@ -35799,6 +35845,11 @@ if test "$wxUSE_ACCEL" = "yes"; then
   USES_CONTROLS=1
 fi
 
+if test "$wxUSE_ACTIVITYINDICATOR" = "yes"; then
+  $as_echo "#define wxUSE_ACTIVITYINDICATOR 1" >>confdefs.h
+
+fi
+
 if test "$wxUSE_ADDREMOVECTRL" = "yes"; then
   $as_echo "#define wxUSE_ADDREMOVECTRL 1" >>confdefs.h