docs: Remove Photon remnants

Also get rid of some platform references made irrelevant by the removal
of their respective platform specific GUI code.

runtime/doc/eval.txt

@@ -6714,7 +6714,6 @@ gui_gtk			Compiled with GTK+ GUI (any version).
 gui_gtk2		Compiled with GTK+ 2 GUI (gui_gtk is also defined).
 gui_mac			Compiled with Macintosh GUI.
 gui_motif		Compiled with Motif GUI.
-gui_photon		Compiled with Photon GUI.
 gui_running		Vim is running in the GUI, or it will start soon.
 gui_win32		Compiled with MS Windows Win32 GUI.
 gui_win32s		idem, and Win32s system being used (Windows 3.1)

runtime/doc/gui.txt

@@ -24,9 +24,7 @@ Other GUI documentation:
 1. Starting the GUI				*gui-start* *E229* *E233*
 
 First you must make sure you actually have a version of Vim with the GUI code
-included.  You can check this with the ":version" command, it says "with xxx
+included.
-GUI", where "xxx" is X11-Motif, X11-Athena, Photon, GTK, GTK2, etc., or
-"MS-Windows 32 bit GUI version".
 
 How to start the GUI depends on the system used.  Mostly you can run the
 GUI version of Vim with:
@@ -690,13 +688,10 @@ because the item will never be selected.  Use a single colon to keep it
 simple.
 
 							*gui-toolbar*
-The toolbar is currently available in the Win32, Athena, Motif, GTK+ (X11),
+The default toolbar is setup in menu.vim.  The display of the toolbar is
-and Photon GUI.  It should turn up in other GUIs in due course.  The
+controlled by the 'guioptions' letter 'T'.  You can thus have menu & toolbar
-default toolbar is setup in menu.vim.
+together, or either on its own, or neither.  The appearance is controlled by
-The display of the toolbar is controlled by the 'guioptions' letter 'T'.  You
+the 'toolbar' option.  You can choose between an image, text or both.
-can thus have menu & toolbar together, or either on its own, or neither.
-The appearance is controlled by the 'toolbar' option.  You can choose between
-an image, text or both.
 
 							*toolbar-icon*
 The toolbar is defined as a special menu called ToolBar, which only has one
@@ -779,9 +774,9 @@ from the main menu bar.  You must then use the |:popup| or |:tearoff| command
 to display it.
 
 							*popup-menu*
-In the Win32, GTK+, Motif, Athena and Photon GUI, you can define the
+You can define the special menu "PopUp".  This is the menu that is displayed
-special menu "PopUp".  This is the menu that is displayed when the right mouse
+when the right mouse button is pressed, if 'mousemodel' is set to popup or
-button is pressed, if 'mousemodel' is set to popup or popup_setpos.
+popup_setpos.
 
 
 5.3 Showing What Menus Are Mapped To			*showing-menus*

runtime/doc/options.txt

@@ -3451,7 +3451,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 	the case of X).  The font names given should be "normal" fonts.  Vim
 	will try to find the related bold and italic fonts.
 
-	For Win32, GTK, Motif, Mac OS and Photon: >
+	For Win32, GTK, Motif, and Mac OS: >
 	    :set guifont=*
 <	will bring up a font requester, where you can pick the font you want.
 
@@ -3648,7 +3648,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 	  't'	Include tearoff menu items.  Currently only works for Win32,
 		GTK+, and Motif 1.2 GUI.
 								*'go-T'*
-	  'T'	Include Toolbar.  Currently only in Win32, GTK+, Motif, Photon
+	  'T'	Include Toolbar.  Currently only in Win32, GTK+, Motif,
 		and Athena GUIs.
 								*'go-r'*
 	  'r'	Right-hand scrollbar is always present.
@@ -7321,8 +7321,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 				*'toolbar'* *'tb'*
 'toolbar' 'tb'		string	(default "icons,tooltips")
 			global
-			{only for |+GUI_GTK|, |+GUI_Athena|, |+GUI_Motif| and
+			{only for |+GUI_GTK|, |+GUI_Athena|, and |+GUI_Motif|}
-			|+GUI_Photon|}
 	The contents of this option controls various toolbar settings.  The
 	possible values are:
 		icons		Toolbar buttons are shown with icons.
@@ -7993,7 +7992,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 'winaltkeys' 'wak'	string	(default "menu")
 			global
 			{not in Vi}
-			{only used in Win32, Motif, GTK and Photon GUI}
+			{only used in Win32, Motif, and GTK}
 	Some GUI versions allow the access to menu entries by using the ALT
 	key in combination with a character that appears underlined in the
 	menu.  This conflicts with the use of the ALT key for mappings and

runtime/doc/todo.txt

@@ -3741,7 +3741,7 @@ Win32 GUI:
 
 
 GUI:
-8   Make inputdialog() work for Photon, Amiga.
+8   Make inputdialog() work for Amiga.
 -   <C--> cannot be mapped.  Should be possible to recognize this as a
     normal "-" with the Ctrl modifier.
 7   Implement ":popup" for other systems than Windows.

runtime/menu.vim

@@ -383,7 +383,7 @@ if has("keymap")
   endif
   unlet s:n
 endif
-if has("win32") || has("win16") || has("gui_motif") || has("gui_gtk") || has("gui_kde") || has("gui_photon") || has("gui_mac")
+if has("win32") || has("win16") || has("gui_motif") || has("gui_gtk") || has("gui_kde") || has("gui_mac")
   an 20.470 &Edit.Select\ Fo&nt\.\.\.	:set guifont=*<CR>
 endif
 

src/nvim/normal.c

@@ -2102,7 +2102,7 @@ do_mouse (
        * Windows only shows the popup menu on the button up event.
        */
 #if defined(FEAT_GUI_MOTIF) || defined(FEAT_GUI_GTK) \
-      || defined(FEAT_GUI_PHOTON) || defined(FEAT_GUI_MAC)
+      || defined(FEAT_GUI_MAC)
       if (!is_click)
         return false;
 #endif