RangeSelect/MultiSelect: (Breaking) Fix + Rename ImGuiMultiSelectFlags_NoMultiSelect to ImGuiMultiSelectFlags_SingleSelect as it seems easier to grasp.

Feature was broken by "Tidying up..." June 30 commit.

imgui.h

@@ -2661,12 +2661,12 @@ struct ImColor
 #define IMGUI_HAS_MULTI_SELECT      // Multi-Select/Range-Select WIP branch // <-- This is currently _not_ in the top of imgui.h to prevent merge conflicts.
 
 // Flags for BeginMultiSelect().
-// (we provide 'ImGuiMultiSelectFlags_NoMultiSelect' for consistency and flexiblity, but it essentially disable the main purpose of BeginMultiSelect().
+// (we provide 'ImGuiMultiSelectFlags_SingleSelect' for consistency and flexiblity to allow a single-selection to use same code/logic, but it essentially disable the biggest purpose of BeginMultiSelect().
-//  If you use 'ImGuiMultiSelectFlags_NoMultiSelect' you can handle single-selection in a simpler way by just calling Selectable()/TreeNode() and reacting on clicks).
+//  If you use 'ImGuiMultiSelectFlags_SingleSelect' you can handle single-selection in a simpler way by just calling Selectable()/TreeNode() and reacting on clicks).
 enum ImGuiMultiSelectFlags_
 {
     ImGuiMultiSelectFlags_None                  = 0,
-    ImGuiMultiSelectFlags_NoMultiSelect         = 1 << 0,   // Disable selecting more than one item. This is not very useful at this kind of selection can be implemented without BeginMultiSelect(), but this is available for consistency.
+    ImGuiMultiSelectFlags_SingleSelect          = 1 << 0,   // Disable selecting more than one item. This is available to allow single-selection code to use same code/logic is desired, but may not be very useful.
     ImGuiMultiSelectFlags_NoSelectAll           = 1 << 1,   // Disable CTRL+A shortcut to set RequestSelectAll
     ImGuiMultiSelectFlags_ClearOnEscape         = 1 << 2,   // Clear selection when pressing Escape while scope is focused.
     ImGuiMultiSelectFlags_ClearOnClickWindowVoid= 1 << 3,   // Clear selection when clicking on empty location within host window (use if BeginMultiSelect() covers a whole window)

imgui_demo.cpp

@@ -3086,7 +3086,7 @@ static void ShowDemoWindowMultiSelect()
             ImGui::Checkbox("Enable drag & drop", &use_drag_drop);
             ImGui::Checkbox("Show in a table", &show_in_table);
             ImGui::Checkbox("Show color button", &show_color_button);
-            ImGui::CheckboxFlags("ImGuiMultiSelectFlags_NoMultiSelect", &flags, ImGuiMultiSelectFlags_NoMultiSelect);
+            ImGui::CheckboxFlags("ImGuiMultiSelectFlags_SingleSelect", &flags, ImGuiMultiSelectFlags_SingleSelect);
             ImGui::CheckboxFlags("ImGuiMultiSelectFlags_NoSelectAll", &flags, ImGuiMultiSelectFlags_NoSelectAll);
             ImGui::CheckboxFlags("ImGuiMultiSelectFlags_ClearOnEscape", &flags, ImGuiMultiSelectFlags_ClearOnEscape);
             ImGui::CheckboxFlags("ImGuiMultiSelectFlags_ClearOnClickWindowVoid", &flags, ImGuiMultiSelectFlags_ClearOnClickWindowVoid);

imgui_widgets.cpp

@@ -7063,7 +7063,7 @@ ImGuiMultiSelectIO* ImGui::BeginMultiSelect(ImGuiMultiSelectFlags flags)
     }
 
     // Shortcut: Select all (CTRL+A)
-    if (!(flags & ImGuiMultiSelectFlags_NoMultiSelect) && !(flags & ImGuiMultiSelectFlags_NoSelectAll))
+    if (!(flags & ImGuiMultiSelectFlags_SingleSelect) && !(flags & ImGuiMultiSelectFlags_NoSelectAll))
         if (Shortcut(ImGuiMod_Ctrl | ImGuiKey_A))
             ms->BeginIO.RequestSelectAll = true;
 
@@ -7215,7 +7215,7 @@ void ImGui::MultiSelectItemFooter(ImGuiID id, bool* p_selected, bool* p_pressed)
 
     void* item_data = (void*)g.NextItemData.SelectionUserData;
 
-    const bool is_multiselect = (ms->Flags & ImGuiMultiSelectFlags_NoMultiSelect) == 0;
+    const bool is_multiselect = (ms->Flags & ImGuiMultiSelectFlags_SingleSelect) == 0;
     bool is_ctrl = (ms->KeyMods & ImGuiMod_Ctrl) != 0;
     bool is_shift = (ms->KeyMods & ImGuiMod_Shift) != 0;
 
@@ -7294,19 +7294,21 @@ void ImGui::MultiSelectItemFooter(ImGuiID id, bool* p_selected, bool* p_pressed)
             ms->EndIO.RangeDirection = +1;
         }
 
-        if (input_source == ImGuiInputSource_Mouse || g.NavActivateId == id)
+        if (!is_multiselect)
         {
-            if (is_multiselect && !is_ctrl)
             ms->EndIO.RequestClear = true;
         }
-        else if (input_source == ImGuiInputSource_Keyboard || input_source == ImGuiInputSource_Gamepad)
+        else if (input_source == ImGuiInputSource_Mouse || g.NavActivateId == id)
         {
-            if (is_multiselect && is_shift && !is_ctrl) // Without Shift the RequestClear was done in BeginIO, not necessary to do again.
+            if (!is_ctrl)
                 ms->EndIO.RequestClear = true;
         }
-        else if (!is_multiselect)
+        else if (input_source == ImGuiInputSource_Keyboard || input_source == ImGuiInputSource_Gamepad)
+        {
+            if (is_shift && !is_ctrl) // Without Shift the RequestClear was done in BeginIO, not necessary to do again.
                 ms->EndIO.RequestClear = true;
         }
+    }
 
     // Update/store the selection state of the Source item (used by CTRL+SHIFT, when Source is unselected we perform a range unselect)
     if (storage->RangeSrcItem == item_data)