Selectable: Added ImGuiSelectableFlags_Disabled flag in the public API. (#211)

CHANGELOG.txt

@@ -59,6 +59,7 @@ Other Changes:
  - Drag and Drop: Payload stays available and under the mouse if the source stops being submitted, however the tooltip is replaced by "...". (#1725)
  - Drag and Drop: Added ImGuiDragDropFlags_SourceAutoExpirePayload flag to force payload to expire if the source stops being submitted. (#1725, #143).
  - IsItemHovered(): Added ImGuiHoveredFlags_AllowWhenDisabled flag to query hovered status on disabled items. (#1940, #211)
+ - Selectable: Added ImGuiSelectableFlags_Disabled flag in the public API. (#211)
  - Misc: Added ImGuiMouseCursor_Hand cursor enum + corresponding software cursor. (#1913, 1914) [@aiekick, @ocornut] 
  - Misc: Tweaked software mouse cursor offset to match the offset of the corresponding Windows 10 cursors.
  - Made assertion more clear when trying to call Begin() outside of the NewFrame()..EndFrame() scope. (#1987)

imgui.h

@@ -686,7 +686,8 @@ enum ImGuiSelectableFlags_
     ImGuiSelectableFlags_None               = 0,
     ImGuiSelectableFlags_DontClosePopups    = 1 << 0,   // Clicking this don't close parent popup window
     ImGuiSelectableFlags_SpanAllColumns     = 1 << 1,   // Selectable frame can span all columns (text will still fit in current column)
-    ImGuiSelectableFlags_AllowDoubleClick   = 1 << 2    // Generate press events on double clicks too
+    ImGuiSelectableFlags_AllowDoubleClick   = 1 << 2,   // Generate press events on double clicks too
+    ImGuiSelectableFlags_Disabled           = 1 << 3    // Cannot be selected, display greyed out text
 };
 
 // Flags for ImGui::BeginCombo()

imgui_internal.h

@@ -251,8 +251,7 @@ enum ImGuiSelectableFlagsPrivate_
     ImGuiSelectableFlags_NoHoldingActiveID  = 1 << 10,
     ImGuiSelectableFlags_PressedOnClick     = 1 << 11,
     ImGuiSelectableFlags_PressedOnRelease   = 1 << 12,
-    ImGuiSelectableFlags_Disabled           = 1 << 13,
-    ImGuiSelectableFlags_DrawFillAvailWidth = 1 << 14
+    ImGuiSelectableFlags_DrawFillAvailWidth = 1 << 13
 };
 
 enum ImGuiSeparatorFlags_