Move the help links to the action row as round buttons

Review feedback: the two links are easier to find on the panel's action
row than in the header, and the same placement can then be reused for
the rest of the UI.

The icons become the glyph alone, white on a solid teal disc, so they
read as links rather than as more of the panel's grey tool icons. ImGui
clamps an image button's frame rounding to its frame padding, so the
disc is drawn underneath on its own draw-list channel, which also lets
it carry the hover and pressed feedback.

resources/images/texture_displacement_video_guide.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 16 16"><path d="M6 4.1 12.2 8 6 11.9z" style="fill:none;stroke:#f2f2f2;stroke-width:1.5;stroke-linecap:round;stroke-linejoin:round"/></svg>

resources/images/texture_displacement_wiki.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 16 16"><circle cx="8" cy="3.6" r="1" style="fill:#f2f2f2"/><path d="M8 6.6v5.8" style="fill:none;stroke:#f2f2f2;stroke-width:1.8;stroke-linecap:round"/></svg>

src/slic3r/GUI/Gizmos/GLGizmoTextureDisplacement.cpp

@@ -3396,6 +3396,8 @@ void GLGizmoTextureDisplacement::ensure_panel_icons()
         "texture_displacement_adjust.svg", "canvas_drag.svg", "texture_displacement_move_up.svg",
         "texture_displacement_move_down.svg", "texture_displacement_drag.svg",
         "texture_displacement_select_all.svg", "texture_displacement_erase_all.svg",
+        // Help links on the action row: the wiki page and the video walkthrough.
+        "texture_displacement_video_guide.svg", "texture_displacement_wiki.svg",
     };
     std::vector<std::string> paths;
     paths.reserve(names.size());
@@ -5439,6 +5441,47 @@ void GLGizmoTextureDisplacement::on_render_input_window(float x, float y, float
             m_imgui->tooltip(tip_text, wrap_w);
         return clicked;
     };
+    // Round link button: a white glyph on a solid teal disc, for the help links on the action row.
+    // ImGui clamps an image button's frame rounding to its frame padding, so the disc cannot be the
+    // button's own background; it is drawn underneath on a separate draw-list channel, which is what
+    // lets it be filled in after the button has reported its hover state.
+    const auto link_button = [&](int uid, const std::string &iconfile, float sz, const wxString &label,
+                                 const wxString &tip_text) -> bool {
+        const auto  it      = m_panel_icon_map.find(iconfile);
+        const float pad     = std::max(1.f, std::round(sz * 0.26f));
+        ImDrawList *dl      = ImGui::GetWindowDrawList();
+        bool        clicked = false;
+        dl->ChannelsSplit(2);
+        dl->ChannelsSetCurrent(1);
+        ImGui::PushID(uid);
+        ImGui::PushStyleVar(ImGuiStyleVar_FrameBorderSize, 0.f);
+        ImGui::PushStyleColor(ImGuiCol_Button, ImVec4(0.f, 0.f, 0.f, 0.f));
+        ImGui::PushStyleColor(ImGuiCol_ButtonHovered, ImVec4(0.f, 0.f, 0.f, 0.f));
+        ImGui::PushStyleColor(ImGuiCol_ButtonActive, ImVec4(0.f, 0.f, 0.f, 0.f));
+        if (it != m_panel_icon_map.end() && !it->second.empty() && it->second[0]->is_valid()) {
+            const IconManager::Icon &ic = *it->second[0];
+            clicked = m_imgui->image_button((ImTextureID) (intptr_t) ic.tex_id, ImVec2(sz - 2.f * pad, sz - 2.f * pad),
+                                            ic.tl, ic.br, int(pad));
+        } else {
+            clicked = ImGui::Button(label.ToUTF8().data(), ImVec2(0.f, sz));
+        }
+        ImGui::PopStyleColor(3);
+        ImGui::PopStyleVar();
+        ImGui::PopID();
+        // The disc is the button's whole surface, so it has to carry the hover feedback that the
+        // transparent ImGui background no longer gives: lighter under the cursor, darker while held.
+        const bool   hovered = ImGui::IsItemHovered();
+        const float  lift    = ImGui::IsItemActive() ? -0.12f : hovered ? 0.18f : 0.f;
+        const auto   shade   = [lift](float c) { return lift >= 0.f ? c + (1.f - c) * lift : c * (1.f + lift); };
+        const ImVec2 lo = ImGui::GetItemRectMin(), hi = ImGui::GetItemRectMax();
+        dl->ChannelsSetCurrent(0);
+        dl->AddCircleFilled(ImVec2(0.5f * (lo.x + hi.x), 0.5f * (lo.y + hi.y)), 0.5f * (hi.y - lo.y),
+                            ImGui::GetColorU32(ImVec4(shade(orca.x), shade(orca.y), shade(orca.z), orca.w)));
+        dl->ChannelsMerge();
+        if (!tip_text.empty() && hovered)
+            m_imgui->tooltip(tip_text, wrap_w);
+        return clicked;
+    };
     // A short vertical rule between groups of buttons on one row; call it right after an item.
     const auto vsep = [&](float h) {
         ImGui::SameLine(0.f, gap_s);
@@ -6890,7 +6933,22 @@ void GLGizmoTextureDisplacement::on_render_input_window(float x, float y, float
         }
 
         const float button_h = std::round(frame_h * 1.25f);
-        const float third    = std::floor((panel_w - style.ItemSpacing.x) / 3.f);
+
+        // The help links lead the action row rather than sitting in the header: this row is the part of
+        // the panel that is always on screen, so a user who does not yet know the guide exists still
+        // passes over it on the way to Bake.
+        if (link_button(807, "texture_displacement_wiki.svg", button_h, _L("Documentation"),
+                        _L("Open the texture displacement page of the OrcaSlicer wiki. Opens in your browser.")))
+            wxLaunchDefaultBrowser("https://www.orcaslicer.com/wiki/print_prepare/prepare_texture_displacement.html");
+        ImGui::SameLine(0.f, gap_s);
+        if (link_button(808, "texture_displacement_video_guide.svg", button_h, _L("Video guide"),
+                        _L("Watch the texture displacement walkthrough on YouTube. Opens in your browser.")))
+            wxLaunchDefaultBrowser("https://www.youtube.com/watch?v=D7w3tG1kdvE");
+        ImGui::SameLine();
+
+        // Close and Bake keep their 1:2 split, over whatever the links left of the row.
+        const float links_w = 2.f * button_h + gap_s + style.ItemSpacing.x;
+        const float third   = std::floor((panel_w - links_w - style.ItemSpacing.x) / 3.f);
         if (busy) {
             if (ImGui::Button((_u8L("Stop") + "##stop").c_str(), ImVec2(third, button_h)))
                 wxGetApp().plater()->get_ui_job_worker().cancel_all();