Added ImGuiWindowFlags_UnsavedDocument window flag to append '*' to title without altering the ID, as a convenience to avoid using the ### operator. (merged from Docking branch)

Author: ocornut

docs/CHANGELOG.txt

@@ -39,6 +39,8 @@ Breaking Changes:
   The addition of new configuration options in the Docking branch is pushing for a little reorganization of those names.
 
 Other Changes:
+- Added ImGuiWindowFlags_UnsavedDocument window flag to append '*' to title without altering 
+  the ID, as a convenience to avoid using the ### operator.
 - Resizing windows from edge is now enabled by default (io.ConfigWindowsResizeFromEdges=true). Note that 
   it only works _if_ the back-end sets ImGuiBackendFlags_HasMouseCursors, which the standard back-end do.
 - Added io.ConfigWindowsMoveFromTitleBarOnly option. Still is ignored by window with no title bars (often popups).

imgui.cpp

@@ -5093,8 +5093,11 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
             window->DC.NavLayerCurrentMask = (1 << ImGuiNavLayer_Main);
             window->DC.ItemFlags = item_flags_backup;
 
-            // Title text (FIXME: refactor text alignment facilities along with RenderText helpers, this is too much code for what it does.)
-            ImVec2 text_size = CalcTextSize(name, NULL, true);
+            // Title bar text (with: horizontal alignment, avoiding collapse/close button, optional "unsaved document" marker)
+            // FIXME: Refactor text alignment facilities along with RenderText helpers, this is too much code..
+            const char* UNSAVED_DOCUMENT_MARKER = "*";
+            float marker_size_x = (flags & ImGuiWindowFlags_UnsavedDocument) ? CalcTextSize(UNSAVED_DOCUMENT_MARKER, NULL, false).x : 0.0f;
+            ImVec2 text_size = CalcTextSize(name, NULL, true) + ImVec2(marker_size_x, 0.0f);
             ImRect text_r = title_bar_rect;
             float pad_left = (flags & ImGuiWindowFlags_NoCollapse) ? style.FramePadding.x : (style.FramePadding.x + g.FontSize + style.ItemInnerSpacing.x);
             float pad_right = (p_open == NULL)                     ? style.FramePadding.x : (style.FramePadding.x + g.FontSize + style.ItemInnerSpacing.x);
@@ -5105,6 +5108,12 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
             ImRect clip_rect = text_r;
             clip_rect.Max.x = window->Pos.x + window->Size.x - (p_open ? title_bar_rect.GetHeight() - 3 : style.FramePadding.x); // Match the size of CloseButton()
             RenderTextClipped(text_r.Min, text_r.Max, name, NULL, &text_size, style.WindowTitleAlign, &clip_rect);
+            if (flags & ImGuiWindowFlags_UnsavedDocument)
+            {
+                ImVec2 marker_pos = ImVec2(ImMax(text_r.Min.x, text_r.Min.x + (text_r.GetWidth() - text_size.x) * style.WindowTitleAlign.x) + text_size.x, text_r.Min.y) + ImVec2(2 - marker_size_x, 0.0f);
+                ImVec2 off = ImVec2(0.0f, (float)(int)(-g.FontSize * 0.25f));
+                RenderTextClipped(marker_pos + off, text_r.Max + off, UNSAVED_DOCUMENT_MARKER, NULL, NULL, ImVec2(0, style.WindowTitleAlign.y), &clip_rect);
+            }
         }
 
         // Save clipped aabb so we can access it in constant-time in FindHoveredWindow()

imgui.h

@@ -665,6 +665,7 @@ enum ImGuiWindowFlags_
     ImGuiWindowFlags_AlwaysUseWindowPadding = 1 << 16,  // Ensure child windows without border uses style.WindowPadding (ignored by default for non-bordered child windows, because more convenient)
     ImGuiWindowFlags_NoNavInputs            = 1 << 18,  // No gamepad/keyboard navigation within the window
     ImGuiWindowFlags_NoNavFocus             = 1 << 19,  // No focusing toward this window with gamepad/keyboard navigation (e.g. skipped by CTRL+TAB)
+    ImGuiWindowFlags_UnsavedDocument        = 1 << 20,  // Append '*' to title without affecting the ID, as a convenience to avoid using the ### operator. When used in a tab/docking context, tab is selected on closure and closure is deferred by one frame to allow code to cancel the closure (with a confirmation popup, etc.) without flicker.
     ImGuiWindowFlags_NoNav                  = ImGuiWindowFlags_NoNavInputs | ImGuiWindowFlags_NoNavFocus,
     ImGuiWindowFlags_NoDecoration           = ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoScrollbar | ImGuiWindowFlags_NoCollapse,
     ImGuiWindowFlags_NoInputs               = ImGuiWindowFlags_NoMouseInputs | ImGuiWindowFlags_NoNavInputs | ImGuiWindowFlags_NoNavFocus,