BeginCombo(): Added ImGuiComboFlags_NoArrowButton and ImGuiComboFlags_NoPreview flags + hover color matches drag and sliders.

CHANGELOG.txt

@@ -112,6 +112,10 @@ Other Changes:
 - Drag and Drop: Increased payload type string to 12 characters instead of 8. (#143)
 - Drag and Drop: TreeNode as drop target displays rectangle over full frame. (#1597, #143)
 - DragFloat: Fix/workaround for backends which do not preserve a valid mouse position when dragged out of bounds. (#1559)
+- Slider, Combo: Use ImGuiCol_FrameBgHovered color when hovered. (#1456) [@stfx]
+- Combo: BeginCombo(): Added ImGuiComboFlags_NoArrowButton to disable the arrow button and only display the wide value preview box.
+- Combo: BeginCombo(): Added ImGuiComboFlags_NoPreview to disable the preview and only display a square arrow button. 
+- Combo: Arrow button isn't displayed over frame background so its blended color matches other buttons. Left side of the button isn't rounded.
 - PlotLines: plot a flat line if scale_min==scale_max. (#1621)
 - ImFontAtlas: Handle stb_truetype stbtt_InitFont() and stbtt_PackBegin() possible failures more gracefully, GetTexDataAsRGBA32() won't crash during conversion. (#1527)
 - ImFontAtlas: Moved mouse cursor data out of ImGuiContext, fix drawing them with multiple contexts. Also remove the last remaining undesirable dependency on ImGui in imgui_draw.cpp. (#939)

imgui.cpp

@@ -8562,7 +8562,7 @@ bool ImGui::SliderBehavior(const ImRect& frame_bb, ImGuiID id, float* v, float v
     const ImGuiStyle& style = g.Style;
 
     // Draw frame
-    const ImU32 frame_col = GetColorU32((g.ActiveId == id ) ? ImGuiCol_FrameBgActive : g.HoveredId == id ? ImGuiCol_FrameBgHovered : ImGuiCol_FrameBg);
+    const ImU32 frame_col = GetColorU32(g.ActiveId == id ? ImGuiCol_FrameBgActive : g.HoveredId == id ? ImGuiCol_FrameBgHovered : ImGuiCol_FrameBg);
     RenderNavHighlight(frame_bb, id);
     RenderFrame(frame_bb.Min, frame_bb.Max, frame_col, true, style.FrameRounding);
 
@@ -10573,16 +10573,19 @@ bool ImGui::BeginCombo(const char* label, const char* preview_value, ImGuiComboF
     ImGuiContext& g = *GImGui;
     ImGuiCond backup_next_window_size_constraint = g.NextWindowData.SizeConstraintCond;
     g.NextWindowData.SizeConstraintCond = 0;
-        
+
     ImGuiWindow* window = GetCurrentWindow();
     if (window->SkipItems)
         return false;
 
+    IM_ASSERT((flags & (ImGuiComboFlags_NoArrowButton | ImGuiComboFlags_NoPreview)) != (ImGuiComboFlags_NoArrowButton | ImGuiComboFlags_NoPreview)); // Can't use both flags together
+
     const ImGuiStyle& style = g.Style;
     const ImGuiID id = window->GetID(label);
-    const float w = CalcItemWidth();
 
+    const float arrow_size = (flags & ImGuiComboFlags_NoArrowButton) ? 0.0f : GetFrameHeight();
     const ImVec2 label_size = CalcTextSize(label, NULL, true);
+    const float w = (flags & ImGuiComboFlags_NoPreview) ? arrow_size : CalcItemWidth();
     const ImRect frame_bb(window->DC.CursorPos, window->DC.CursorPos + ImVec2(w, label_size.y + style.FramePadding.y*2.0f));
     const ImRect total_bb(frame_bb.Min, frame_bb.Max + ImVec2(label_size.x > 0.0f ? style.ItemInnerSpacing.x + label_size.x : 0.0f, 0.0f));
     ItemSize(total_bb, style.FramePadding.y);
@@ -10593,14 +10596,18 @@ bool ImGui::BeginCombo(const char* label, const char* preview_value, ImGuiComboF
     bool pressed = ButtonBehavior(frame_bb, id, &hovered, &held);
     bool popup_open = IsPopupOpen(id);
 
-    const float arrow_size = GetFrameHeight();
     const ImRect value_bb(frame_bb.Min, frame_bb.Max - ImVec2(arrow_size, 0.0f));
+    const ImU32 frame_col = GetColorU32(hovered ? ImGuiCol_FrameBgHovered : ImGuiCol_FrameBg);
     RenderNavHighlight(frame_bb, id);
-    window->DrawList->AddRectFilled(frame_bb.Min, ImVec2(frame_bb.Max.x - arrow_size, frame_bb.Max.y), GetColorU32(ImGuiCol_FrameBg), style.FrameRounding, ImDrawCornerFlags_Left);
-    window->DrawList->AddRectFilled(ImVec2(frame_bb.Max.x - arrow_size, frame_bb.Min.y), frame_bb.Max, GetColorU32(popup_open || hovered ? ImGuiCol_ButtonHovered : ImGuiCol_Button), style.FrameRounding, (w <= arrow_size) ? ImDrawCornerFlags_All : ImDrawCornerFlags_Right);
+    if (!(flags & ImGuiComboFlags_NoPreview))
+        window->DrawList->AddRectFilled(frame_bb.Min, ImVec2(frame_bb.Max.x - arrow_size, frame_bb.Max.y), frame_col, style.FrameRounding, ImDrawCornerFlags_Left);
+    if (!(flags & ImGuiComboFlags_NoArrowButton))
+    {
+        window->DrawList->AddRectFilled(ImVec2(frame_bb.Max.x - arrow_size, frame_bb.Min.y), frame_bb.Max, GetColorU32((popup_open || hovered) ? ImGuiCol_ButtonHovered : ImGuiCol_Button), style.FrameRounding, (w <= arrow_size) ? ImDrawCornerFlags_All : ImDrawCornerFlags_Right);
+        RenderArrow(ImVec2(frame_bb.Max.x - arrow_size + style.FramePadding.y, frame_bb.Min.y + style.FramePadding.y), ImGuiDir_Down);
+    }
     RenderFrameBorder(frame_bb.Min, frame_bb.Max, style.FrameRounding);
-    RenderArrow(ImVec2(frame_bb.Max.x - arrow_size + style.FramePadding.y, frame_bb.Min.y + style.FramePadding.y), ImGuiDir_Down);
-    if (preview_value != NULL)
+    if (preview_value != NULL && !(flags & ImGuiComboFlags_NoPreview))
         RenderTextClipped(frame_bb.Min + style.FramePadding, value_bb.Max, preview_value, NULL, NULL, ImVec2(0.0f,0.0f));
     if (label_size.x > 0)
         RenderText(ImVec2(frame_bb.Max.x + style.ItemInnerSpacing.x, frame_bb.Min.y + style.FramePadding.y), label);

imgui.h

@@ -639,6 +639,8 @@ enum ImGuiComboFlags_
     ImGuiComboFlags_HeightRegular           = 1 << 2,   // Max ~8 items visible (default)
     ImGuiComboFlags_HeightLarge             = 1 << 3,   // Max ~20 items visible
     ImGuiComboFlags_HeightLargest           = 1 << 4,   // As many fitting items as possible
+    ImGuiComboFlags_NoArrowButton           = 1 << 5,   // Display on the preview box without the square arrow button
+    ImGuiComboFlags_NoPreview               = 1 << 6,   // Display only a square arrow button
     ImGuiComboFlags_HeightMask_             = ImGuiComboFlags_HeightSmall | ImGuiComboFlags_HeightRegular | ImGuiComboFlags_HeightLarge | ImGuiComboFlags_HeightLargest
 };