change how we handle clicks above top margin

app.lua

@@ -361,6 +361,7 @@ function App.run_tests()
   for _,name in ipairs(sorted_names) do
     App.initialize_for_test()
 --?     print('=== '..name)
+--?     _G[name]()
     xpcall(_G[name], function(err) prepend_debug_info_to_test_failure(name, err) end)
   end
   -- clean up all test methods

edit.lua

@@ -227,6 +227,17 @@ function edit.mouse_press(State, x,y, mouse_button)
     return
   end
 
+  if y < State.top then
+    State.old_cursor1 = State.cursor1
+    State.old_selection1 = State.selection1
+    State.mousepress_shift = App.shift_down()
+    State.selection1 = {
+        line=1,
+        pos=1,
+    }
+    return
+  end
+
   for line_index,line in ipairs(State.lines) do
     if line.mode == 'text' then
       if Text.in_line(State, line_index, x,y) then

select.lua

@@ -74,6 +74,9 @@ function Text.mouse_pos(State)
 end
 
 function Text.to_pos(State, x,y)
+  if y < State.line_cache[State.screen_top1.line].starty then
+    return State.screen_top1.line, State.screen_top1.pos
+  end
   for line_index,line in ipairs(State.lines) do
     if line.mode == 'text' then
       if Text.in_line(State, line_index, x,y) then

text_tests.lua

@@ -1,4 +1,6 @@
 -- major tests for text editing flows
+-- Arguably this should be called edit_tests.lua,
+-- but that would mess up the git blame at this point.
 
 function test_initial_state()
   App.screen.init{width=120, height=60}
@@ -828,6 +830,23 @@ function test_select_text_using_mouse()
   check_eq(Editor_state.cursor1.pos, 4, 'cursor:pos')
 end
 
+function test_select_text_using_mouse_starting_above_text()
+  App.screen.init{width=50, height=60}
+  Editor_state = edit.initialize_test_state()
+  Editor_state.lines = load_array{'abc', 'def', 'xyz'}
+  Text.redraw_all(Editor_state)
+  Editor_state.cursor1 = {line=1, pos=1}
+  Editor_state.screen_top1 = {line=1, pos=1}
+  Editor_state.screen_bottom1 = {}
+  Editor_state.selection1 = {}
+  edit.draw(Editor_state)  -- populate line_cache.starty for each line Editor_state.line_cache
+  -- press mouse above first line of text
+  edit.run_after_mouse_press(Editor_state, Editor_state.left+8,5, 1)
+  check(Editor_state.selection1.line ~= nil, 'selection:line-not-nil')
+  check_eq(Editor_state.selection1.line, 1, 'selection:line')
+  check_eq(Editor_state.selection1.pos, 1, 'selection:pos')
+end
+
 function test_select_text_using_mouse_and_shift()
   App.screen.init{width=50, height=60}
   Editor_state = edit.initialize_test_state()
@@ -904,30 +923,6 @@ function test_select_all_text()
   check_eq(Editor_state.cursor1.pos, 8, 'cursor:pos')
 end
 
---? function test_select_all_text_then_mouse_press_outside_text()
---?   -- display a single line of text
---?   App.screen.init{width=75, height=80}
---?   Editor_state = edit.initialize_test_state()
---?   Editor_state.lines = load_array{'abc def'}
---?   Text.redraw_all(Editor_state)
---?   Editor_state.cursor1 = {line=1, pos=1}
---?   Editor_state.screen_top1 = {line=1, pos=1}
---?   Editor_state.screen_bottom1 = {}
---?   edit.draw(Editor_state)
---?   -- select all
---?   App.fake_key_press('lctrl')
---?   edit.run_after_keychord(Editor_state, 'C-a')
---?   App.fake_key_release('lctrl')
---?   edit.key_release(Editor_state, 'lctrl')
---?   -- selection
---?   check_eq(Editor_state.selection1.line, 1, 'selection:line')
---?   check_eq(Editor_state.selection1.pos, 1, 'selection:pos')
---?   check_eq(Editor_state.cursor1.line, 1, 'cursor:line')
---?   check_eq(Editor_state.cursor1.pos, 8, 'cursor:pos')
---?   -- part of a mouse click outside the selected line
---?   edit.run_after_mouse_press(Editor_state, 45, Margin_top + Editor_state.line_height + 10, --[[mouse button]] 1)
---? end
-
 function test_cut_without_selection()
   -- display a few lines
   App.screen.init{width=Editor_state.left+30, height=60}