feat(ui): add window.blend option for controllin float transparency (#1227)

Closes #1126

Signed-off-by: Tomas Slusny <slusnucky@gmail.com>

Author: deathbeam

README.md

@@ -468,6 +468,7 @@ Below are all available configuration options with their default values:
     title = 'Copilot Chat', -- title of chat window
     footer = nil, -- footer of chat window
     zindex = 1, -- determines if window is on top or below other floating windows
+    blend = 0, -- window blend (transparency), 0-100, 0 is opaque, 100 is fully transparent
   },
 
   show_help = true, -- Shows help message as virtual lines when waiting for user input

lua/CopilotChat/config.lua

@@ -11,6 +11,7 @@
 ---@field title string?
 ---@field footer string?
 ---@field zindex number?
+---@field blend number?
 
 ---@class CopilotChat.config.Shared
 ---@field system_prompt string?
@@ -81,6 +82,7 @@ return {
     title = 'Copilot Chat', -- title of chat window
     footer = nil, -- footer of chat window
     zindex = 1, -- determines if window is on top or below other floating windows
+    blend = 0, -- window blend (transparency), 0-100, 0 is opaque, 100 is fully transparent
   },
 
   show_help = true, -- Shows help message as virtual lines when waiting for user input

lua/CopilotChat/ui/chat.lua

@@ -289,6 +289,7 @@ function Chat:open(config)
     }
 
     self.winnr = vim.api.nvim_open_win(self.bufnr, false, win_opts)
+    vim.wo[self.winnr].winblend = window.blend or 0
   elseif layout == 'vertical' then
     local orig = vim.api.nvim_get_current_win()
     local cmd = 'vsplit'