Eliminate skin updates in between activities

1) Adds way to pop activity without refreshing the skin at
the same time.

Activities are sometimes popped in immediate succession,
or one activity is popped before another one is pushed right
away. This can lead to the UI appearing glitchy, due to an
activity only appearing for a split-second, which is especially
noticeable with complex skins that change the dimensions
of the UI viewport depending on the current activity

To fix this, prevent superfluous skin updates

* when switching between:
- WPS and browser
- WPS and Playlist Catalogue
- WPS and playlist
- WPS and Settings/System/Plugins

* when accessing Track Info or when displaying
bookmarks using the context menu on the WPS

* when switching from QuickScreen to Shortcuts Menu

2) The playlist viewer activity was pushed & popped
redundantly by playlist_view.

----
NB:
Behavior has remained unchanged in all instances of the
code where pop_current_activity() has been replaced by
pop_current_activity(ACTIVITY_REFRESH_NOW).

Change-Id: I56b517b8c9dba823a9fed3a3f558d7469dcea9fd

1 files changed, 7 insertions, 1 deletions

diff --git a/apps/misc.h b/apps/misc.h
index af520a7fd1..4f4527f686 100644
--- a/apps/misc.h
+++ b/apps/misc.h
@@ -214,8 +214,14 @@ struct mp3entry;
 int id3_get_replaygain_mode(const struct mp3entry *id3);
 void replaygain_update(void);
 
+enum activity_refresh
+{
+    ACTIVITY_REFRESH_DEFERRED = 0,
+    ACTIVITY_REFRESH_NOW,
+};
+
 void push_current_activity(enum current_activity screen);
-void pop_current_activity(void);
+void pop_current_activity(enum activity_refresh refresh);
 enum current_activity get_current_activity(void);
 
 /* format a sound value like: -1.05 dB */