feat(termdebug): improve `:Evaluate` floating window (#26621)

Problem:
- The :Evaluate result window is not cleaned up when the cursor moves.
- This window is not focusable.

Solution:
Replace the old implementation from autozimu/LanguageClient-neovim with
vim.lsp.util.open_floating_preview and implement custom focusing logic.
Also remove g:termdebug_useFloatingHover option now that it's working
correctly.

1 files changed, 3 insertions, 5 deletions

diff --git a/runtime/doc/nvim_terminal_emulator.txt b/runtime/doc/nvim_terminal_emulator.txt
index 67e5e53c95..557e714ddc 100644
--- a/runtime/doc/nvim_terminal_emulator.txt
+++ b/runtime/doc/nvim_terminal_emulator.txt
@@ -240,7 +240,7 @@ gdb window and use a "print" command, e.g.: >
 If mouse pointer movements are working, Vim will also show a balloon when the
 mouse rests on text that can be evaluated by gdb.
 You can also use the "K" mapping that will either use Nvim floating windows
-if available to show the results or print below the status bar.
+to show the results.
 
 Now go back to the source window and put the cursor on the first line after
 the for loop, then type: >
@@ -320,6 +320,8 @@ Inspecting variables ~
 
 This is similar to using "print" in the gdb window.
 You can usually shorten `:Evaluate` to `:Ev`.
+The result is displayed in a floating window.
+You can move the cursor to this window by running `:Evaluate` (or `K`) again.
 
 
 Navigating stack frames ~
@@ -475,10 +477,6 @@ If the command needs an argument use a List: >vim
 If there is no g:termdebug_config you can use: >vim
 	let g:termdebugger = ['rr', 'replay', '--']
 
-To not use Nvim floating windows for previewing variable evaluation, set the
-`g:termdebug_useFloatingHover` variable like this: >vim
-	let g:termdebug_useFloatingHover = 0
-
 If you are a mouse person, you can also define a mapping using your right
 click to one of the terminal command like evaluate the variable under the
 cursor: >vim