Add dark mode customization / appearance preferences panel

Add new preference that allows specifying how MacVim will use dark mode:
use systems preference (default), force light mode, force dark mode, or
use Vim's 'background' option to decide. Preference will be stored in
defaults as 'MMAppearanceModeSelection'. Add docs for that as well.

Also, add a new preferences panel called "Appearance" to allow setting
the dark mode setting, and transparent titlebar as well. Setting it will
refresh all Vim windows immediately for feedback.

Also, when setting titlebars to transparent, also hide the file icon as
it's distracting in what's a more minimalistic display. Don't use
another preference for that for now to avoid having too many options.

Minor: Remove preference panel's cross-fade effect as it's more
distracting than useful.

Fix #912

Also:
- See #1015 for part of the contribution.
- Close #266
- Close #933

Author: ychin

runtime/doc/gui_mac.txt

@@ -9,18 +9,19 @@ The MacVim Graphical User Interface			*macvim* *gui-macvim*
  1. MacVim differences		|macvim-differences|
  2. Starting MacVim		|macvim-start|
  3. Preferences			|macvim-preferences|
- 4. Special colors		|macvim-colors|
- 5. Menus			|macvim-menus|
- 6. Toolbar			|macvim-toolbar|
- 7. Touch Bar			|macvim-touchbar|
- 8. Dialogs			|macvim-dialogs|
- 9. System services		|macvim-services|
-10. mvim:// URL handler		|macvim-url-handler|
-11. Keyboard shortcuts		|macvim-shortcuts|
-12. Trackpad gestures		|macvim-gestures|
-13. International		|macvim-international|
-14. Known bugs/missing features	|macvim-todo|
-15. Hints			|macvim-hints|
+ 4. MacVim appearance		|macvim-appearance|
+ 5. Special colors		|macvim-colors|
+ 6. Menus			|macvim-menus|
+ 7. Toolbar			|macvim-toolbar|
+ 8. Touch Bar			|macvim-touchbar|
+ 9. Dialogs			|macvim-dialogs|
+10. System services		|macvim-services|
+11. mvim:// URL handler		|macvim-url-handler|
+12. Keyboard shortcuts		|macvim-shortcuts|
+13. Trackpad gestures		|macvim-gestures|
+14. International		|macvim-international|
+15. Known bugs/missing features	|macvim-todo|
+16. Hints			|macvim-hints|
 
 Other relevant documentation:
 |gui.txt|	For generic items of the GUI.
@@ -259,6 +260,7 @@ KEY				VALUE ~
 *MMNoFontSubstitution*		disable automatic font substitution [bool]
 *MMNoTitleBarWindow*		hide title bar [bool]
 *MMTitlebarAppearsTransparent*	enable a transparent titlebar [bool]
+*MMAppearanceModeSelection*	dark mode selection (|macvim-dark-mode|)[bool]
 *MMShareFindPboard*		share search text to Find Pasteboard [bool]
 *MMShowAddTabButton*		enable "add tab" button on tabline [bool]
 *MMTabMaxWidth*			maximum width of a tab [int]
@@ -301,7 +303,19 @@ shell is used, then "-l" is automatically added as an argument.  To override
 this behaviour set MMLoginShellArgument to "--".
 
 ==============================================================================
-4. Special colors					*macvim-colors*
+4. MacVim appearance					*macvim-appearance*
+
+				*macvim-appearance-mode* *macvim-dark-mode*
+MacVim will by default use the system apperance mode (light or dark). However,
+you can manually force MacVim to use either light or dark mode in the
+preferences panel. A fourth option allows MacVim to respect the |'background'|
+option set by Vim, which is more flexible in situations like loading a dark
+color scheme while system preferences are configured to use light mode. It's
+also the recommended setting when title bar is configured to be "Transparent"
+(see |MMTitlebarAppearsTransparent|).
+
+==============================================================================
+5. Special colors					*macvim-colors*
 
 The colors in MacVim are defined in two dictionaries inside the "Resources"
 folder of the application bundle (MacVim.app/Contents/Resources).  It is
@@ -351,7 +365,7 @@ the "Appearance" pane of the System Preferences.  It also changes the
 highlight color when a window becomes inactive.
 
 ==============================================================================
-5. Menus						*macvim-menus*
+6. Menus						*macvim-menus*
 
 Menus in macOS behave slightly different from other platforms.  For that
 reason two new commands have been added to Vim.  To understand what these
@@ -474,7 +488,7 @@ _cycleWindows:			Select next window (similar to <D-`>)
 _cycleWindowsBackwards:		Select previous window (similar to <D-S-`>)
 
 ==============================================================================
-6. Toolbar						*macvim-toolbar*
+7. Toolbar						*macvim-toolbar*
 
 The toolbar in MacVim works just like in the other GUIs (see |gui-toolbar|),
 with the addition of two separator items (see |menu-separator|).  You can use
@@ -498,7 +512,7 @@ Note: Only a subset of the builtin toolbar items presently have icons.  If no
 icon can be found a warning triangle is displayed instead.
 
 ==============================================================================
-7. Touch Bar						*macvim-touchbar*
+8. Touch Bar						*macvim-touchbar*
 
 Touch Bar in MacVim works similar to the toolbar (see |macvim-toolbar|).  The
 difference is that you use the special menu "TouchBar" instead of "ToolBar": >
@@ -536,7 +550,7 @@ ExitFullScreen		|'fullscreen'| mode. To disable the button, add the
 			  let g:macvim_default_touchbar_fullscreen=0
 
 ==============================================================================
-8. Dialogs						*macvim-dialogs*
+9. Dialogs						*macvim-dialogs*
 
 Dialogs can be controlled with the keyboard in two ways.  By default each
 button in a dialog is bound to a key.  The button that is highlighted by blue
@@ -555,7 +569,7 @@ select the current button.  The current button is indicated with a blue
 outline.
 
 ==============================================================================
-9. System services					*macvim-services*
+10. System services					*macvim-services*
 
 MacVim supports two system services.  These can be accessed from the MacVim
 submenu in the Services menu or by right-clicking a selection.  For services
@@ -572,7 +586,7 @@ The services respect the "Open files from applications" setting in the general
 preferences.
 
 ==============================================================================
-10. mvim:// URL handler				*mvim://* *macvim-url-handler*
+11. mvim:// URL handler				*mvim://* *macvim-url-handler*
 
 MacVim supports a custom URL handler for "mvim://" URLs. The handler is
 supposed to be compatible to TextMate's URL scheme as documented at >
@@ -593,7 +607,7 @@ will open the file /etc/profile on line 20 when clicked in a web browser.
 Note that url has to be a file:// url pointing to an existing local file.
 
 ==============================================================================
-11. Keyboard shortcuts					*macvim-shortcuts*
+12. Keyboard shortcuts					*macvim-shortcuts*
 
 Most keyboard shortcuts in MacVim are bound to menu items and can be
 discovered by looking through the menus (see |macvim-menus| on how to create
@@ -673,7 +687,7 @@ sometimes be slightly involved.  Here are all the things you need to consider:
 - A few command key mappings are set up by MacVim, see |cmd-movement|.
 
 ==============================================================================
-12. Trackpad gestures					*macvim-gestures*
+13. Trackpad gestures					*macvim-gestures*
 
 MacVim supports trackpad swipe gestures.  By default this can be used to
 navigate back/forward in the help (try it!).
@@ -708,7 +722,7 @@ As another example, here is how to switch buffers by swiping left/right: >
 See the section on |key-mapping| for more help on how to map keys.
 
 ==============================================================================
-13. International					*macvim-international*
+14. International					*macvim-international*
 
 When editing non-English text it may be convenient to keep separate keyboard
 layouts for normal and insert mode.  This is supported via the 'imd' option on
@@ -729,7 +743,7 @@ wrong layout when going back to normal mode, then select the layout you want
 to use in normal mode and type ":set imd" followed by ":set noimd".
 
 ==============================================================================
-14. Known bugs/missing features				*macvim-todo*
+15. Known bugs/missing features				*macvim-todo*
 
 This list is by no means exhaustive, it only enumerates some of the more
 prominent bugs/missing features.
@@ -760,7 +774,7 @@ This is also the best place for making feature requests as well as for asking
 general questions about MacVim.
 
 ==============================================================================
-15. Hints						*macvim-hints*
+16. Hints						*macvim-hints*
 
 In this section some general (not necessarily MacVim specific) hints are
 given.

runtime/doc/tags

@@ -4957,6 +4957,7 @@ LogiPat-flags	pi_logipat.txt	/*LogiPat-flags*
 Lua	if_lua.txt	/*Lua*
 M	motion.txt	/*M*
 MDI	starting.txt	/*MDI*
+MMAppearanceModeSelection	gui_mac.txt	/*MMAppearanceModeSelection*
 MMCellWidthMultiplier	gui_mac.txt	/*MMCellWidthMultiplier*
 MMDialogsTrackPwd	gui_mac.txt	/*MMDialogsTrackPwd*
 MMDisableLaunchAnimation	gui_mac.txt	/*MMDisableLaunchAnimation*
@@ -7728,12 +7729,15 @@ mac-vimfile	os_mac.txt	/*mac-vimfile*
 macintosh	os_mac.txt	/*macintosh*
 macro	map.txt	/*macro*
 macvim	gui_mac.txt	/*macvim*
+macvim-appearance	gui_mac.txt	/*macvim-appearance*
+macvim-appearance-mode	gui_mac.txt	/*macvim-appearance-mode*
 macvim-autocommands	gui_mac.txt	/*macvim-autocommands*
 macvim-backspace	gui_mac.txt	/*macvim-backspace*
 macvim-clientserver	remote.txt	/*macvim-clientserver*
 macvim-colors	gui_mac.txt	/*macvim-colors*
 macvim-colorscheme	gui_mac.txt	/*macvim-colorscheme*
 macvim-commands	gui_mac.txt	/*macvim-commands*
+macvim-dark-mode	gui_mac.txt	/*macvim-dark-mode*
 macvim-default-menu	gui_mac.txt	/*macvim-default-menu*
 macvim-delete	gui_mac.txt	/*macvim-delete*
 macvim-dialogs	gui_mac.txt	/*macvim-dialogs*

src/MacVim/English.lproj/Preferences.nib/designable.nib

@@ -47,6 +47,8 @@
 - (NSArray *)filterOpenFiles:(NSArray *)filenames;
 - (BOOL)openFiles:(NSArray *)filenames withArguments:(NSDictionary *)args;
 
+- (void)refreshAllAppearances;
+
 - (IBAction)newWindow:(id)sender;
 - (IBAction)newWindowAndActivate:(id)sender;
 - (IBAction)fileOpen:(id)sender;

src/MacVim/English.lproj/Preferences.nib/keyedobjects.nib

@@ -1072,6 +1072,15 @@ - (BOOL)openFiles:(NSArray *)filenames withArguments:(NSDictionary *)args
     return openOk;
 }
 
+- (void)refreshAllAppearances
+{
+    unsigned count = [vimControllers count];
+    for (unsigned i = 0; i < count; ++i) {
+        MMVimController *vc = [vimControllers objectAtIndex:i];
+        [vc.windowController refreshApperanceMode];
+    }
+}
+
 - (IBAction)newWindow:(id)sender
 {
     ASLogDebug(@"Open new window");

src/MacVim/MMAppController.h

@@ -1236,6 +1236,14 @@ - (void)setBlurRadius:(int)radius
     [self queueMessage:SetBlurRadiusMsgID data:data];
 }
 
+- (void)setBackground:(int)dark
+{
+    NSMutableData *data = [NSMutableData data];
+    [data appendBytes:&dark length:sizeof(int)];
+
+    [self queueMessage:SetBackgroundOptionMsgID data:data];
+}
+
 - (void)updateModifiedFlag
 {
     int state = [self checkForModifiedBuffers];