feat(ui-ext): make 'mousehide' into proper ui_option (#25532)

runtime/doc/ui.txt

@@ -211,6 +211,7 @@ the editor.
 	- 'guifontwide'
 	- 'linespace'
 	- 'mousefocus'
+	- 'mousehide'
 	- 'mousemoveevent'
 	- 'pumblend'
 	- 'showtabline'

src/nvim/option_vars.h

@@ -571,6 +571,7 @@ EXTERN char *p_mouse;           ///< 'mouse'
 EXTERN char *p_mousem;          ///< 'mousemodel'
 EXTERN int p_mousemev;          ///< 'mousemoveevent'
 EXTERN int p_mousef;            ///< 'mousefocus'
+EXTERN int p_mh;                ///< 'mousehide'
 EXTERN char *p_mousescroll;     ///< 'mousescroll'
 EXTERN OptInt p_mousescroll_vert INIT(= MOUSESCROLL_VERT_DFLT);
 EXTERN OptInt p_mousescroll_hor INIT(= MOUSESCROLL_HOR_DFLT);

src/nvim/options.lua

@@ -5452,9 +5452,11 @@ return {
       ]=],
       enable_if = false,
       full_name = 'mousehide',
+      redraw = { 'ui_option' },
       scope = { 'global' },
       short_desc = N_('hide mouse pointer while typing'),
       type = 'bool',
+      varname = 'p_mh',
     },
     {
       abbreviation = 'mousem',

test/functional/ui/options_spec.lua

@@ -19,6 +19,7 @@ describe('UI receives option updates', function()
       linespace=0,
       pumblend=0,
       mousefocus=false,
+      mousehide=true,
       mousemoveevent=false,
       showtabline=1,
       termguicolors=false,
@@ -133,6 +134,12 @@ describe('UI receives option updates', function()
       eq(expected, screen.options)
     end)
 
+    command("set nomousehide")
+    expected.mousehide = false
+    screen:expect(function()
+      eq(expected, screen.options)
+    end)
+
     command("set mousemoveevent")
     expected.mousemoveevent = true
     screen:expect(function()