select cursor pane by clicking on it

edit.lua

@@ -9,7 +9,6 @@ Highlight_color = {r=0.7, g=0.7, b=0.9}  -- selected text
 Icon_color = {r=0.7, g=0.7, b=0.7}  -- color of current mode icon in drawings
 Help_color = {r=0, g=0.5, b=0}
 Help_background_color = {r=0, g=0.5, b=0, a=0.1}
-Editor_background_color = {r=0.9, g=0.9, b=0, a=0.1}
 
 Margin_left = 25
 Margin_right = 25

main.lua

@@ -9,6 +9,8 @@ require 'button'
 require 'main_tests'
 
 Column_header_color = {r=0.4, g=0.4, b=0.4}
+Pane_background_color = {r=0.9, g=0.9, b=0, a=0.1}
+Cursor_pane_background_color = {r=0.5, g=0.5, b=0, a=0.1}
 
 -- The note-taking app has a few differences with the baseline editor it's
 -- forked from:
@@ -58,6 +60,8 @@ function App.initialize_globals()
 
   Pan = {}
 
+  Cursor_pane = nil  -- surface column and row index, along with some cached data
+
   -- resize
   Last_resize_time = nil
 
@@ -165,11 +169,11 @@ function App.draw()
   -- top > Margin_top or Screen_top.line > 1
   local x = Padding_horizontal + Margin_left
 --?   print('draw')
-  for _, column in ipairs(Surface) do
+  for column_index, column in ipairs(Surface) do
     if overlap(x, x+Display_settings.column_width, Display_settings.x, Display_settings.x + App.screen.width) then
 --?       print('draw column')
       local y = Margin_top
-      for _, pane in ipairs(column) do
+      for pane_index, pane in ipairs(column) do
         if overlap(y, y + Margin_above + Cache[pane.id].height + Margin_below, Display_settings.y, Display_settings.y + App.screen.height) then
 --?           print('draw pane')
           pane.top = y - Display_settings.y + Margin_above
@@ -178,7 +182,11 @@ function App.draw()
           pane.width = pane.right - pane.left
           -- TODO: update pane.screen_top1 and pane.cursor1
           edit.draw(pane)
-          App.color(Editor_background_color)
+          if Cursor_pane and column_index == Cursor_pane.col and pane_index == Cursor_pane.row then
+            App.color(Cursor_pane_background_color)
+          else
+            App.color(Pane_background_color)
+          end
           love.graphics.rectangle('fill', pane.left-Margin_left,pane.top-Margin_above, pane.width+Margin_left+Margin_right, pane.bottom-pane.top+Margin_above+Margin_below)
         end
         y = y + Margin_above + Cache[pane.id].height + Margin_below + Padding_vertical
@@ -238,6 +246,7 @@ function App.update(dt)
 end
 
 function in_pane(x,y)
+  -- duplicate some logic from App.draw
   local sx,sy = to_surface(x,y)
   local x = Padding_horizontal
   for column_idx, column in ipairs(Surface) do
@@ -261,6 +270,31 @@ function in_pane(x,y)
   return false
 end
 
+function to_pane(x,y)
+  -- duplicate some logic from App.draw
+  local sx,sy = to_surface(x,y)
+  local x = Padding_horizontal
+  for column_idx, column in ipairs(Surface) do
+    if sx < x then
+      return nil
+    end
+    if sx < x + Margin_left + Display_settings.column_width + Margin_right then
+      local y = Margin_top
+      for pane_idx, pane in ipairs(column) do
+        if sy < y then
+          return nil
+        end
+        if sy < y + Margin_above + Cache[pane.id].height + Margin_below then
+          return {col=column_idx, row=pane_idx}
+        end
+        y = y + Margin_above + Cache[pane.id].height + Margin_below + Padding_vertical
+      end
+    end
+    x = x + Margin_left + Display_settings.column_width + Margin_right + Padding_horizontal
+  end
+  return false
+end
+
 function to_surface(x, y)
   return x+Display_settings.x, y+Display_settings.y
 end
@@ -292,7 +326,9 @@ function App.mousepressed(x,y, mouse_button)
     return
   end
   local sx,sy = to_surface(x,y)
-  if not in_pane(x,y) then
+  if in_pane(x,y) then
+    Cursor_pane = to_pane(sx,sy)
+  else
     Pan = {x=sx, y=sy}
     return
   end