Fullscreen Editor (new fullscreen mode for clean UI)

Organize Maximize/Fullscreen mess and add a new fullscreen mode with no UI

* Maximize Editor: (old Ctrl+Up)
* Full Screen Window: (old Alt + F11)
* Full Screen Editor: new operator (Alt + F10)
* Change Show/Hide Header: (Alt + F9)

When the mode is on moving the mouse near the top right corner of the
editor shows an icon to go back to the normal editor mode.

This was originally intended for the multiview branch, but this
functionality also benefits non-stereo workflows, thus it can be
reviewed and committed independently.

Development notes:
* This includes cleanups in the code to sanitize the naming of
  fullscreen/maximize across the window/editor code.

* Originally the idea was to make the window fullscreen as well, but
  this idea was dropped.

* You can see the clicking area when debug is 1

* Technically the user can be left with an unfaded icon in the corner
  (specially when using a tablet). If we think this is too bad we can
  increase the action zone to be the whole screen, or something similar.

Reviewers: campbellbarton [1], ton [2], fsiddi [2]

[1] actual code review
[2] design review

Differential Revision: https://developer.blender.org/D678

1 files changed, 9 insertions, 5 deletions

diff --git a/source/blender/makesdna/DNA_screen_types.h b/source/blender/makesdna/DNA_screen_types.h
index 8a900c3946e..47a08c62f95 100644
--- a/source/blender/makesdna/DNA_screen_types.h
+++ b/source/blender/makesdna/DNA_screen_types.h
@@ -60,7 +60,7 @@ typedef struct bScreen {
 	int redraws_flag;					/* user-setting for which editors get redrawn during anim playback (used to be time->redraws) */
 	int pad1;
 	
-	short full;							/* temp screen for image render display or fileselect */
+	short state;						/* temp screen for image render display or fileselect */
 	short temp;							/* temp screen in a temp window, don't save (like user prefs) */
 	short winid;						/* winid from WM, starts with 1 */
 	short do_draw;						/* notifier for drawing edges */
@@ -247,7 +247,8 @@ typedef struct ARegion {
 	short do_draw_overlay;		/* private, cached notifier events */
 	short swap;					/* private, indicator to survive swap-exchange */
 	short overlap;				/* private, set for indicate drawing overlapped */
-	short pad[2];
+	short flagfullscreen;		/* temporary copy of flag settings for clean fullscreen */
+	short pad;
 	
 	struct ARegionType *type;	/* callbacks for this region type */
 	
@@ -287,9 +288,12 @@ typedef struct ARegion {
 #define HEADERDOWN	1
 #define HEADERTOP	2
 
-/* screen->full */
-#define SCREENNORMAL	0
-#define SCREENFULL		1
+/* screen->state */
+enum {
+	SCREENNORMAL     = 0,
+	SCREENMAXIMIZED  = 1, /* one editor taking over the screen */
+	SCREENFULL       = 2, /* one editor taking over the screen with no bare-minimum UI elements */
+};
 
 /* Panel->flag */
 enum {