diff --git a/AGENTS.md b/AGENTS.md
index 59aeed878b..fbc624b958 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -30,6 +30,7 @@ ctest --test-dir ./tests/fff_print
 - C++17, selective C++20. PascalCase classes, snake_case functions/variables
 - `#pragma once` for headers. Smart pointers and RAII preferred
 - Parallelization via TBB — be mindful of shared state
+- Always use `SetSizerAndFit(sizer)` instead of `SetSizer(sizer)` on top level window. Unless `SetSizer` must be called before the full layout is built, call `sizer->SetSizeHints(window)` afterwards in this case.
 
 ## Key Entry Points
 
diff --git a/src/slic3r/GUI/BindDialog.cpp b/src/slic3r/GUI/BindDialog.cpp
index 4d3e4fc6d5..a4b568e82d 100644
--- a/src/slic3r/GUI/BindDialog.cpp
+++ b/src/slic3r/GUI/BindDialog.cpp
@@ -192,7 +192,7 @@ PingCodeBindDialog::PingCodeBindDialog(Plater* plater /*= nullptr*/)
 
 
 
-    SetSizer(sizer_main);
+    SetSizerAndFit(sizer_main);
     Layout();
     Fit();
 
@@ -670,7 +670,7 @@ PingCodeBindDialog::~PingCodeBindDialog() {
      m_sizer_main->Add(m_sw_bind_failed_info, 0, wxALIGN_CENTER, 0);
      m_sizer_main->Add(m_simplebook, 0, wxALIGN_RIGHT | wxRIGHT | wxBOTTOM, ButtonProps::ChoiceButtonGap());
 
-     SetSizer(m_sizer_main);
+     SetSizerAndFit(m_sizer_main);
      Layout();
      Fit();
      Centre(wxBOTH);
@@ -992,7 +992,7 @@ UnBindMachineDialog::UnBindMachineDialog(Plater *plater /*= nullptr*/)
      m_sizer_main->Add(m_sizer_button, 0, wxALIGN_RIGHT | wxRIGHT, ButtonProps::ChoiceButtonGap());
      m_sizer_main->Add(0, 0, 0, wxTOP, FromDIP(20));
 
-     SetSizer(m_sizer_main);
+     SetSizerAndFit(m_sizer_main);
      Layout();
      Fit();
      Centre(wxBOTH);
diff --git a/src/slic3r/GUI/CaliHistoryDialog.cpp b/src/slic3r/GUI/CaliHistoryDialog.cpp
index 2e7f2caf97..4de90d8b8f 100644
--- a/src/slic3r/GUI/CaliHistoryDialog.cpp
+++ b/src/slic3r/GUI/CaliHistoryDialog.cpp
@@ -632,9 +632,8 @@ EditCalibrationHistoryDialog::EditCalibrationHistoryDialog(wxWindow
 
     main_sizer->Add(top_panel, 1, wxEXPAND | wxALL, FromDIP(20));
 
-    SetSizer(main_sizer);
+    SetSizerAndFit(main_sizer);
     Layout();
-    Fit();
     CenterOnParent();
 
     wxGetApp().UpdateDlgDarkUI(this);
@@ -910,9 +909,8 @@ NewCalibrationHistoryDialog::NewCalibrationHistoryDialog(wxWindow *parent, const
 
     main_sizer->Add(top_panel, 1, wxEXPAND | wxALL, FromDIP(20));
 
-    SetSizer(main_sizer);
+    SetSizerAndFit(main_sizer);
     Layout();
-    Fit();
     CenterOnParent();
 
     wxGetApp().UpdateDlgDarkUI(this);
diff --git a/src/slic3r/GUI/Calibration.cpp b/src/slic3r/GUI/Calibration.cpp
index 4b32d10a02..0c2b4f1659 100644
--- a/src/slic3r/GUI/Calibration.cpp
+++ b/src/slic3r/GUI/Calibration.cpp
@@ -162,7 +162,7 @@ CalibrationDialog::CalibrationDialog(Plater *plater)
     body_panel->Layout();
 
     m_sizer_main->Add(body_panel, 0, wxEXPAND | wxALL, FromDIP(25));
-    SetSizer(m_sizer_main);
+    SetSizerAndFit(m_sizer_main);
     Layout();
     Fit();
 
diff --git a/src/slic3r/GUI/CloneDialog.cpp b/src/slic3r/GUI/CloneDialog.cpp
index 36243249f8..9024f0cb61 100644
--- a/src/slic3r/GUI/CloneDialog.cpp
+++ b/src/slic3r/GUI/CloneDialog.cpp
@@ -112,9 +112,8 @@ CloneDialog::CloneDialog(wxWindow *parent)
 
     v_sizer->Add(bottom_sizer, 0, wxEXPAND);
 
-    this->SetSizer(v_sizer);
+    this->SetSizerAndFit(v_sizer);
     this->Layout();
-    v_sizer->Fit(this);
 
     wxGetApp().UpdateDlgDarkUI(this);
 
diff --git a/src/slic3r/GUI/ConnectPrinter.cpp b/src/slic3r/GUI/ConnectPrinter.cpp
index 338e8d3367..b4cd7f4f2f 100644
--- a/src/slic3r/GUI/ConnectPrinter.cpp
+++ b/src/slic3r/GUI/ConnectPrinter.cpp
@@ -80,9 +80,8 @@ ConnectPrinterDialog::ConnectPrinterDialog(wxWindow *parent, wxWindowID id, cons
 
     main_sizer->Add(sizer_top);
 
-    this->SetSizer(main_sizer);
+    this->SetSizerAndFit(main_sizer);
     this->Layout();
-    this->Fit();
     CentreOnParent();
 
     m_textCtrl_code->Bind(wxEVT_TEXT, &ConnectPrinterDialog::on_input_enter, this);
diff --git a/src/slic3r/GUI/DownloadProgressDialog.cpp b/src/slic3r/GUI/DownloadProgressDialog.cpp
index 02d7a285e3..9bc0d90e5e 100644
--- a/src/slic3r/GUI/DownloadProgressDialog.cpp
+++ b/src/slic3r/GUI/DownloadProgressDialog.cpp
@@ -112,9 +112,8 @@ DownloadProgressDialog::DownloadProgressDialog(wxString title)
     m_simplebook_status->AddPage(m_panel_download_failed, wxEmptyString, false);
     m_simplebook_status->AddPage(m_panel_install_failed, wxEmptyString, false);
 
-    SetSizer(m_sizer_main);
+    SetSizerAndFit(m_sizer_main);
     Layout();
-    Fit();
     CentreOnParent();
 
     Bind(wxEVT_CLOSE_WINDOW, &DownloadProgressDialog::on_close, this);
diff --git a/src/slic3r/GUI/ExtrusionCalibration.cpp b/src/slic3r/GUI/ExtrusionCalibration.cpp
index ca953fe482..cd7f5990a7 100644
--- a/src/slic3r/GUI/ExtrusionCalibration.cpp
+++ b/src/slic3r/GUI/ExtrusionCalibration.cpp
@@ -261,7 +261,7 @@ void ExtrusionCalibration::create()
     top_sizer->Add(FromDIP(24), 0);
     top_sizer->Add(sizer_main, 1, wxEXPAND);
     top_sizer->Add(FromDIP(24), 0);
-    SetSizer(top_sizer);
+    SetSizerAndFit(top_sizer);
 
     // set default nozzle
     m_comboBox_nozzle_dia->SetSelection(1);
@@ -271,7 +271,6 @@ void ExtrusionCalibration::create()
     set_step(1);
 
     Layout();
-    Fit();
 
     m_k_val->GetTextCtrl()->Bind(wxEVT_TEXT_ENTER, [this](wxCommandEvent& e) {
         input_value_finish();
diff --git a/src/slic3r/GUI/FilamentPickerDialog.cpp b/src/slic3r/GUI/FilamentPickerDialog.cpp
index a57e93eea0..98c955fb76 100644
--- a/src/slic3r/GUI/FilamentPickerDialog.cpp
+++ b/src/slic3r/GUI/FilamentPickerDialog.cpp
@@ -105,9 +105,8 @@ FilamentPickerDialog::FilamentPickerDialog(wxWindow *parent, const wxString& fil
     container_sizer->Add(main_sizer, 1, wxEXPAND | wxALL, FromDIP(10));
     container_sizer->Add(dlg_btns, 0, wxEXPAND);
 
-    SetSizer(container_sizer);
+    SetSizerAndFit(container_sizer);
     Layout();
-    container_sizer->Fit(this);
 
     // Position the dialog relative to the parent window
     if (GetParent()) {
diff --git a/src/slic3r/GUI/MsgDialog.cpp b/src/slic3r/GUI/MsgDialog.cpp
index d742e5efd9..ebf4db6846 100644
--- a/src/slic3r/GUI/MsgDialog.cpp
+++ b/src/slic3r/GUI/MsgDialog.cpp
@@ -65,7 +65,7 @@ MsgDialog::MsgDialog(wxWindow *parent, const wxString &title, const wxString &he
     main_sizer->Add(btn_sizer, 0, wxBOTTOM | wxRIGHT | wxEXPAND | wxTOP, FromDIP(10));
 
     apply_style(style);
-	SetSizerAndFit(main_sizer);
+	SetSizer(main_sizer);
     wxGetApp().UpdateDlgDarkUI(this);
 }
 
@@ -221,6 +221,7 @@ void MsgDialog::apply_style(long style)
 
 void MsgDialog::finalize()
 {
+    GetSizer()->SetSizeHints(this);
     Layout();
     Fit();
     CenterOnParent();
@@ -547,7 +548,7 @@ DeleteConfirmDialog::DeleteConfirmDialog(wxWindow *parent, const wxString &title
     m_del_btn->Bind(wxEVT_BUTTON, [this](wxCommandEvent &e) { EndModal(wxID_OK); });
     m_cancel_btn->Bind(wxEVT_BUTTON, [this](wxCommandEvent &e) { EndModal(wxID_CANCEL); });
 
-    SetSizer(m_main_sizer);
+    SetSizerAndFit(m_main_sizer);
     Layout();
     Fit();
     wxGetApp().UpdateDlgDarkUI(this);
@@ -582,7 +583,7 @@ Newer3mfVersionDialog::Newer3mfVersionDialog(wxWindow *parent, const Semver *fil
     main_sizer->Add(content_sizer, 0, wxEXPAND | wxALL, FromDIP(5));
     main_sizer->Add(get_btn_sizer(), 0, wxEXPAND | wxALL, FromDIP(5));
 
-    this->SetSizer(main_sizer);
+    this->SetSizerAndFit(main_sizer);
     Layout();
     Fit();
     wxGetApp().UpdateDlgDarkUI(this);
@@ -745,9 +746,8 @@ NetworkErrorDialog::NetworkErrorDialog(wxWindow* parent)
     sizer_main->Add(sizer_button, 1, wxEXPAND | wxLEFT | wxRIGHT, 15);
     sizer_main->Add(0, 0, 0, wxTOP, 18);
 
-    SetSizer(sizer_main);
+    SetSizerAndFit(sizer_main);
     Layout();
-    sizer_main->Fit(this);
     Centre(wxBOTH);
 }
 
diff --git a/src/slic3r/GUI/NetworkPluginDialog.cpp b/src/slic3r/GUI/NetworkPluginDialog.cpp
index d018af47ba..bc898d0d24 100644
--- a/src/slic3r/GUI/NetworkPluginDialog.cpp
+++ b/src/slic3r/GUI/NetworkPluginDialog.cpp
@@ -47,6 +47,7 @@ NetworkPluginDownloadDialog::NetworkPluginDownloadDialog(wxWindow* parent, Mode
     } else {
         create_missing_plugin_ui();
     }
+    main_sizer->SetSizeHints(this);
     Layout();
     Fit();
     CentreOnParent();
diff --git a/src/slic3r/GUI/NetworkTestDialog.cpp b/src/slic3r/GUI/NetworkTestDialog.cpp
index f4cca3ea95..78f395febc 100644
--- a/src/slic3r/GUI/NetworkTestDialog.cpp
+++ b/src/slic3r/GUI/NetworkTestDialog.cpp
@@ -47,7 +47,7 @@ NetworkTestDialog::NetworkTestDialog(wxWindow* parent, wxWindowID id, const wxSt
 
 	init_bind();
 
-	this->SetSizer(main_sizer);
+	this->SetSizerAndFit(main_sizer);
 	this->Layout();
 
 	this->Centre(wxBOTH);
diff --git a/src/slic3r/GUI/PartSkipDialog.cpp b/src/slic3r/GUI/PartSkipDialog.cpp
index 5820a40c66..b9dd7d5007 100644
--- a/src/slic3r/GUI/PartSkipDialog.cpp
+++ b/src/slic3r/GUI/PartSkipDialog.cpp
@@ -270,7 +270,7 @@ PartSkipDialog::PartSkipDialog(wxWindow *parent) : DPIDialog(parent, wxID_ANY, _
     m_simplebook->AddPage(m_book_third_panel, _("dialog page"), false);
     m_sizer->Add(m_simplebook, 1, wxEXPAND | wxALL, 5);
 
-    SetSizer(m_sizer);
+    SetSizerAndFit(m_sizer);
     m_zoom_in_btn->Bind(wxEVT_BUTTON, &PartSkipDialog::OnZoomIn, this);
     m_zoom_out_btn->Bind(wxEVT_BUTTON, &PartSkipDialog::OnZoomOut, this);
     m_switch_drag_btn->Bind(wxEVT_BUTTON, &PartSkipDialog::OnSwitchDrag, this);
@@ -281,7 +281,6 @@ PartSkipDialog::PartSkipDialog(wxWindow *parent) : DPIDialog(parent, wxID_ANY, _
     m_all_checkbox->Bind(wxEVT_TOGGLEBUTTON, &PartSkipDialog::OnAllCheckbox, this);
 
     Layout();
-    Fit();
     CentreOnParent();
 }
 
diff --git a/src/slic3r/GUI/Plater.cpp b/src/slic3r/GUI/Plater.cpp
index d0a28fdf5e..106c142fea 100644
--- a/src/slic3r/GUI/Plater.cpp
+++ b/src/slic3r/GUI/Plater.cpp
@@ -15134,7 +15134,7 @@ ProjectDropDialog::ProjectDropDialog(const std::string &filename)
 
     m_sizer_main->Add(dlg_btns, 0, wxEXPAND);
 
-    SetSizer(m_sizer_main);
+    SetSizerAndFit(m_sizer_main);
     Layout();
     Fit();
     Centre(wxBOTH);
diff --git a/src/slic3r/GUI/PrintOptionsDialog.cpp b/src/slic3r/GUI/PrintOptionsDialog.cpp
index f86c52e567..349e75fa06 100644
--- a/src/slic3r/GUI/PrintOptionsDialog.cpp
+++ b/src/slic3r/GUI/PrintOptionsDialog.cpp
@@ -28,7 +28,7 @@ PrintOptionsDialog::PrintOptionsDialog(wxWindow* parent)
 {
     this->SetDoubleBuffered(true);
     SetBackgroundColour(*wxWHITE);
-    SetSize(FromDIP(480),FromDIP(520));
+    // SetMinSize(FromDIP(wxSize{wxDefaultCoord,520}));
 
 
     m_scrollwindow = new wxScrolledWindow(this, wxID_ANY);
@@ -50,7 +50,8 @@ PrintOptionsDialog::PrintOptionsDialog(wxWindow* parent)
     m_scrollwindow->FitInside();
 
     this->Layout();
-    // mainSizer->Fit(this);
+    mainSizer->SetMinSize(wxDefaultCoord, FromDIP(520));
+    mainSizer->Fit(this);
     //this->Fit();
 
      m_cb_ai_monitoring->Bind(wxEVT_TOGGLEBUTTON, [this](wxCommandEvent &evt) {
@@ -1670,12 +1671,9 @@ PrinterPartsDialog::PrinterPartsDialog(wxWindow* parent)
     /*inset data*/
     sizer->Add(single_panel, 0, wxEXPAND, 0);
     sizer->Add(multiple_panel, 0, wxEXPAND, 0);
-    SetSizer(sizer);
-    Layout();
-    Fit();
-
     single_panel->Hide();
-
+    SetSizerAndFit(sizer);
+    Layout();
     wxGetApp().UpdateDlgDarkUI(this);
 }
 
@@ -1752,6 +1750,7 @@ bool PrinterPartsDialog::Show(bool show)
             }
         }
 
+        GetSizer()->SetSizeHints(this);
         Layout();
         Fit();
     }
diff --git a/src/slic3r/GUI/PublishDialog.cpp b/src/slic3r/GUI/PublishDialog.cpp
index 6bcab900f2..e14c4484cd 100644
--- a/src/slic3r/GUI/PublishDialog.cpp
+++ b/src/slic3r/GUI/PublishDialog.cpp
@@ -119,7 +119,7 @@ PublishDialog::PublishDialog(Plater *plater)
     top_sizer->Add(m_main_sizer, 1, wxALL | wxEXPAND, 0);
     top_sizer->Add(FromDIP(30), 0, 0, wxEXPAND, 0);
 
-    this->SetSizer(top_sizer);
+    this->SetSizerAndFit(top_sizer);
     this->Layout();
 
     this->Centre(wxBOTH);
diff --git a/src/slic3r/GUI/StepMeshDialog.cpp b/src/slic3r/GUI/StepMeshDialog.cpp
index cd0f4bd423..b1a8e2319a 100644
--- a/src/slic3r/GUI/StepMeshDialog.cpp
+++ b/src/slic3r/GUI/StepMeshDialog.cpp
@@ -310,10 +310,9 @@ StepMeshDialog::StepMeshDialog(wxWindow* parent, Slic3r::Step& file, double line
 
     bSizer->Add(bSizer_button, 1, wxEXPAND);
 
-    this->SetSizer(bSizer);
+    this->SetSizerAndFit(bSizer);
     update_mesh_number_text();
     this->Layout();
-    bSizer->Fit(this);
 
     this->Bind(wxEVT_LEFT_DOWN, [this](auto& e) {
         SetFocusIgnoringChildren();
diff --git a/src/slic3r/GUI/TroubleshootDialog.cpp b/src/slic3r/GUI/TroubleshootDialog.cpp
index 2ddb136a1c..b0a8f71930 100644
--- a/src/slic3r/GUI/TroubleshootDialog.cpp
+++ b/src/slic3r/GUI/TroubleshootDialog.cpp
@@ -354,7 +354,7 @@ TroubleshootDialog::TroubleshootDialog()
     m_sizer->AddSpacer(FromDIP(20));
     m_sizer->Add(right_sizer, 0, wxEXPAND | wxTOP | wxBOTTOM | wxRIGHT, FromDIP(15));
 
-    SetSizer(m_sizer);
+    SetSizerAndFit(m_sizer);
     Layout();
     Fit();
     CenterOnParent();
diff --git a/src/slic3r/GUI/TroubleshootDialog.hpp b/src/slic3r/GUI/TroubleshootDialog.hpp
index c9214ed06a..ab0fcfbadd 100644
--- a/src/slic3r/GUI/TroubleshootDialog.hpp
+++ b/src/slic3r/GUI/TroubleshootDialog.hpp
@@ -168,6 +168,9 @@ private:
         }
         wxClientDC dc(this);
         int cWidth = GetClientSize().GetWidth();
+        // Don't compute/commit a size based on a not-yet-laid-out width
+        // Mirrors the guard in OnPaint() so both use the same wrap results
+        if (cWidth < 50) return;
 
         int y = 0;
         for (size_t i = 0; i < m_lines.size(); ++i) {
diff --git a/src/slic3r/GUI/UnsavedChangesDialog.cpp b/src/slic3r/GUI/UnsavedChangesDialog.cpp
index d4287b9c35..5c69466cfa 100644
--- a/src/slic3r/GUI/UnsavedChangesDialog.cpp
+++ b/src/slic3r/GUI/UnsavedChangesDialog.cpp
@@ -773,7 +773,7 @@ std::vector<std::string> DiffViewCtrl::selected_options()
 
 static std::string none{"none"};
 #define UNSAVE_CHANGE_DIALOG_SCROLL_WINDOW_SIZE wxSize(FromDIP(490), FromDIP(374))
-#define UNSAVE_CHANGE_DIALOG_ACTION_LINE_SIZE wxSize(FromDIP(490), FromDIP(60))
+#define UNSAVE_CHANGE_DIALOG_ACTION_LINE_SIZE wxSize(FromDIP(490), -1)
 #define UNSAVE_CHANGE_DIALOG_FIRST_VALUE_WIDTH FromDIP(190)
 #define UNSAVE_CHANGE_DIALOG_VALUE_WIDTH FromDIP(150)
 #define UNSAVE_CHANGE_DIALOG_ITEM_HEIGHT FromDIP(24)
@@ -1075,11 +1075,6 @@ void UnsavedChangesDialog::build(Preset::Type type, PresetCollection *dependent_
     m_sizer_main->Add(m_sizer_button, 0, wxEXPAND | wxTOP, 6);
     m_sizer_main->Add(0, 0, 1, wxTOP, 18);
 
-    SetSizer(m_sizer_main);
-    Layout();
-    Fit();
-    Centre(wxBOTH);
-
     if (params) {
         if (params->left_to_right)
             update_tree(type, params->config, params->from, params->to);
@@ -1095,6 +1090,11 @@ void UnsavedChangesDialog::build(Preset::Type type, PresetCollection *dependent_
     //topSizer->SetSizeHints(this);
 
     show_info_line(Action::Undef);
+
+    SetSizerAndFit(m_sizer_main);
+    Layout();
+    Fit();
+    // Centre(wxBOTH);
 }
 
 void UnsavedChangesDialog::show_info_line(Action action, std::string preset_name)
@@ -1499,6 +1499,7 @@ void UnsavedChangesDialog::update(Preset::Type type, PresetCollection* dependent
     }
 
     m_action_line->SetLabel(action_msg);
+    m_action_line->Wrap(UNSAVE_CHANGE_DIALOG_SCROLL_WINDOW_SIZE.x);
 
     update_tree(type, presets);
     update_list();
diff --git a/src/slic3r/GUI/UpdateDialogs.cpp b/src/slic3r/GUI/UpdateDialogs.cpp
index e45a83b4c3..0710e054f7 100644
--- a/src/slic3r/GUI/UpdateDialogs.cpp
+++ b/src/slic3r/GUI/UpdateDialogs.cpp
@@ -213,9 +213,8 @@ MsgUpdateConfig::MsgUpdateConfig(const std::vector<Update> &updates, bool force_
     m_scrollwindw_release_note->Layout();
 
 
-    SetSizer(m_sizer_main);
+    SetSizerAndFit(m_sizer_main);
     Layout();
-    m_sizer_main->Fit(this);
 
     Centre(wxBOTH);
 	wxGetApp().UpdateDlgDarkUI(this);