diff --git a/pcb_calculator/calculator_panels/panel_attenuators.cpp b/pcb_calculator/calculator_panels/panel_attenuators.cpp
index 5c19c381e4..644cd9817f 100644
--- a/pcb_calculator/calculator_panels/panel_attenuators.cpp
+++ b/pcb_calculator/calculator_panels/panel_attenuators.cpp
@@ -47,6 +47,7 @@ PANEL_ATTENUATORS::PANEL_ATTENUATORS( wxWindow* parent, wxWindowID id,
     m_AttenuatorList.push_back( new ATTENUATOR_BRIDGE() );
     m_AttenuatorList.push_back( new ATTENUATOR_SPLITTER() );
     m_CurrAttenuator = m_AttenuatorList[0];
+    SetAttenuator( 0 );     // Ensure an attenuator and especially its bitmap are set
 
     m_staticTextAttMsg->SetFont( KIUI::GetInfoFont( this ).Italic() );
 
@@ -55,6 +56,9 @@ PANEL_ATTENUATORS::PANEL_ATTENUATORS( wxWindow* parent, wxWindowID id,
     m_attR1Unit->SetLabel( wxT( "Ω" ) );
     m_attR2Unit->SetLabel( wxT( "Ω" ) );
     m_attR3Unit->SetLabel( wxT( "Ω" ) );
+
+    // Needed on wxWidgets 3.0 to ensure sizers are correctly set
+    GetSizer()->SetSizeHints( this );
 }
 
 
diff --git a/pcb_calculator/calculator_panels/panel_board_class.cpp b/pcb_calculator/calculator_panels/panel_board_class.cpp
index bd5b48d4bf..821d736e90 100644
--- a/pcb_calculator/calculator_panels/panel_board_class.cpp
+++ b/pcb_calculator/calculator_panels/panel_board_class.cpp
@@ -30,6 +30,9 @@ PANEL_BOARD_CLASS::PANEL_BOARD_CLASS( wxWindow* parent, wxWindowID id,
 {
     // Autosize the row label column to be sure label are not truncated
     m_gridClassesValuesDisplay->SetRowLabelSize( wxGRID_AUTOSIZE );
+
+    // Needed on wxWidgets 3.0 to ensure sizers are correctly set
+    GetSizer()->SetSizeHints( this );
 }
 
 
diff --git a/pcb_calculator/calculator_panels/panel_color_code.cpp b/pcb_calculator/calculator_panels/panel_color_code.cpp
index 6160057e6e..d398cc8459 100644
--- a/pcb_calculator/calculator_panels/panel_color_code.cpp
+++ b/pcb_calculator/calculator_panels/panel_color_code.cpp
@@ -30,6 +30,9 @@ PANEL_COLOR_CODE::PANEL_COLOR_CODE( wxWindow* parent, wxWindowID id,
 {
     initColorCodePanel();
     ToleranceSelection( m_rbToleranceSelection->GetSelection() );
+
+    // Needed on wxWidgets 3.0 to ensure sizers are correctly set
+    GetSizer()->SetSizeHints( this );
 }
 
 
diff --git a/pcb_calculator/calculator_panels/panel_electrical_spacing.cpp b/pcb_calculator/calculator_panels/panel_electrical_spacing.cpp
index 033bd07df7..71cfa020e3 100644
--- a/pcb_calculator/calculator_panels/panel_electrical_spacing.cpp
+++ b/pcb_calculator/calculator_panels/panel_electrical_spacing.cpp
@@ -115,6 +115,9 @@ PANEL_ELECTRICAL_SPACING::PANEL_ELECTRICAL_SPACING( wxWindow* parent, wxWindowID
 {
     // Autosize the row label column to be sure label are not truncated
     m_gridElectricalSpacingValues->SetRowLabelSize( wxGRID_AUTOSIZE );
+
+    // Needed on wxWidgets 3.0 to ensure sizers are correctly set
+    GetSizer()->SetSizeHints( this );
 }
 
 
diff --git a/pcb_calculator/calculator_panels/panel_eserie.cpp b/pcb_calculator/calculator_panels/panel_eserie.cpp
index c6715f4512..00c5e86cf9 100644
--- a/pcb_calculator/calculator_panels/panel_eserie.cpp
+++ b/pcb_calculator/calculator_panels/panel_eserie.cpp
@@ -41,6 +41,14 @@ PANEL_E_SERIE::PANEL_E_SERIE( wxWindow* parent, wxWindowID id,
     m_reqResUnits->SetLabel( wxT( "kΩ" ) );
     m_exclude1Units->SetLabel( wxT( "kΩ" ) );
     m_exclude2Units->SetLabel( wxT( "kΩ" ) );
+
+    // show markdown formula explanation in lower help panel
+    wxString msg;
+    ConvertMarkdown2Html( wxGetTranslation( eseries_help ), msg );
+    m_panelESeriesHelp->SetPage( msg );
+
+    // Needed on wxWidgets 3.0 to ensure sizers are correctly set
+    GetSizer()->SetSizeHints( this );
 }
 
 
@@ -63,10 +71,4 @@ void PANEL_E_SERIE::SaveSettings( PCB_CALCULATOR_SETTINGS* aCfg )
 
 void PANEL_E_SERIE::LoadSettings( PCB_CALCULATOR_SETTINGS* aCfg )
 {
-    // initialize ESeries tab at each pcb-calculator start
-    wxString msg;
-
-    // show markdown formula explanation in lower help panel
-    ConvertMarkdown2Html( wxGetTranslation( eseries_help ), msg );
-    m_panelESeriesHelp->SetPage( msg );
 }
diff --git a/pcb_calculator/calculator_panels/panel_regulator.cpp b/pcb_calculator/calculator_panels/panel_regulator.cpp
index 034f698d8d..1bf59d0d85 100644
--- a/pcb_calculator/calculator_panels/panel_regulator.cpp
+++ b/pcb_calculator/calculator_panels/panel_regulator.cpp
@@ -53,6 +53,9 @@ PANEL_REGULATOR::PANEL_REGULATOR( wxWindow* parent, wxWindowID id,
 
     m_choiceRegulatorSelector->Append( m_RegulatorList.GetRegList() );
     SelectLastSelectedRegulator();
+
+    // Needed on wxWidgets 3.0 to ensure sizers are correctly set
+    GetSizer()->SetSizeHints( this );
 }
 
 PANEL_REGULATOR::~PANEL_REGULATOR()
diff --git a/pcb_calculator/calculator_panels/panel_track_width.cpp b/pcb_calculator/calculator_panels/panel_track_width.cpp
index 04d4d2924d..d695319d03 100644
--- a/pcb_calculator/calculator_panels/panel_track_width.cpp
+++ b/pcb_calculator/calculator_panels/panel_track_width.cpp
@@ -58,6 +58,9 @@ PANEL_TRACK_WIDTH::PANEL_TRACK_WIDTH( wxWindow* parent, wxWindowID id,
 
     m_TWMode = TW_MASTER_CURRENT;
     m_TWNested = false;
+
+    // Needed on wxWidgets 3.0 to ensure sizers are correctly set
+    GetSizer()->SetSizeHints( this );
 }
 
 
diff --git a/pcb_calculator/calculator_panels/panel_transline.cpp b/pcb_calculator/calculator_panels/panel_transline.cpp
index 80f568cc38..52f4d73f11 100644
--- a/pcb_calculator/calculator_panels/panel_transline.cpp
+++ b/pcb_calculator/calculator_panels/panel_transline.cpp
@@ -90,6 +90,11 @@ void PANEL_TRANSLINE::LoadSettings( PCB_CALCULATOR_SETTINGS* aCfg )
 
     TranslineTypeSelection( m_currTransLineType );
     m_TranslineSelection->SetSelection( m_currTransLineType );
+
+    // Needed on wxWidgets 3.0 to ensure sizers are correctly set
+    // It also remove a minor cosmetic issue on wxWidgets 3.5 on MSW
+    // Called here after the current selected transline bitmaps are enabled/disabled
+    GetSizer()->SetSizeHints( this );
 }
 
 
diff --git a/pcb_calculator/calculator_panels/panel_via_size.cpp b/pcb_calculator/calculator_panels/panel_via_size.cpp
index 1c003f3492..ddad3512da 100644
--- a/pcb_calculator/calculator_panels/panel_via_size.cpp
+++ b/pcb_calculator/calculator_panels/panel_via_size.cpp
@@ -67,6 +67,9 @@ PANEL_VIA_SIZE::PANEL_VIA_SIZE( wxWindow* parent, wxWindowID id,
     m_viaReactanceUnits->SetLabel( wxT( "Ω" ) );
 
     m_viaBitmap->SetBitmap( KiBitmap( BITMAPS::viacalc ) );
+
+    // Needed on wxWidgets 3.0 to ensure sizers are correctly set
+    GetSizer()->SetSizeHints( this );
 }