I'm using Windows 10, GTK2 works normal, but when I test with GTK 3 it gives the following error.
Compilar pacote LCL 2.0.10: Código saída 1, Erros: 6, Aviso: 9, Dicas: 67
gtk3widgets.pas(255,14) Warning: An inherited method is hidden by "GetPosition:LongInt;"
gtk3widgets.pas(296,14) Warning: An inherited method is hidden by "GetPosition:LongInt;"
gtk3widgets.pas(517,15) Note: Virtual method "InitializeWidget;" has a lower visibility (protected) than parent class TGtk3Widget (public)
gtk3widgets.pas(705,15) Note: Virtual method "InitializeWidget;" has a lower visibility (protected) than parent class TGtk3ToggleButton (public)
gtk3widgets.pas(912,28) Hint: Parameter "widget" not used
gtk3widgets.pas(912,66) Hint: Parameter "data" not used
gtk3widgets.pas(1080,7) Note: Call to subroutine "function GetDebugLogger:TLazLogger;" marked as inline is not inlined
gtk3widgets.pas(1283,7) Note: Call to subroutine "function GetDebugLogger:TLazLogger;" marked as inline is not inlined
gtk3widgets.pas(1286,5) Note: Call to subroutine "function GetDebugLogger:TLazLogger;" marked as inline is not inlined
gtk3widgets.pas(1312,3) Note: Local variable "ARect" is assigned but never used
gtk3widgets.pas(1402,15) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(1424,21) Hint: Local variable "MoveMsg" does not seem to be initialized
gtk3widgets.pas(1365,28) Hint: Parameter "AWidget" not used
gtk3widgets.pas(1459,15) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(1449,26) Hint: Parameter "AWidget" not used
gtk3widgets.pas(1477,15) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(1467,26) Hint: Parameter "AWidget" not used
gtk3widgets.pas(1556,23) Hint: Conversion between ordinals and pointers is not portable
gtk3widgets.pas(1594,17) Hint: Local variable "MessE" does not seem to be initialized
gtk3widgets.pas(1563,26) Hint: Parameter "AWidget" not used
gtk3widgets.pas(398,33) Hint: Parameter "Params" not used
gtk3widgets.pas(391,33) Hint: Parameter "Params" not used
gtk3widgets.pas(1649,15) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(1689,15) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(1724,15) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(1728,19) Hint: Local variable "AStruct" does not seem to be initialized
gtk3widgets.pas(1784,4) Note: User defined: Currently TGtk3DeviceContext(Msg.DC).Translate(P) is creating incorrect offsets inside TPages for TLabel and maybe others
gtk3widgets.pas(132,49) Hint: Parameter "Event" not used
gtk3widgets.pas(1826,15) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(1838,15) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(146,26) Hint: Parameter "AWidget" not used
gtk3widgets.pas(1967,15) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(2059,6) Warning: User defined: workaround for GtkTreeView key bindings.Must find out what LCL does with this keys.
gtk3widgets.pas(2097,21) Hint: Local variable "CharMsg" does not seem to be initialized
gtk3widgets.pas(1954,3) Note: Local variable "KeyCode" not used
gtk3widgets.pas(1955,3) Note: Local variable "AShiftState" not used
gtk3widgets.pas(2161,15) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(2277,3) Note: Local variable "R" not used
gtk3widgets.pas(2278,3) Note: Local variable "G" not used
gtk3widgets.pas(2279,3) Note: Local variable "B" not used
gtk3widgets.pas(2435,4) Note: User defined: Gtk3: Find a nice way to assign StyleContext
gtk3widgets.pas(89,31) Hint: Parameter "AValue" not used
gtk3widgets.pas(97,23) Hint: Parameter "AValue" not used
gtk3widgets.pas(2456,22) Error: Calling convention doesn't match forward
gtk3widgets.pas(92,14) Error: Found declaration: QueryInterface(constref TGuid;out <Formal type>):LongInt; StdCall;
gtk3widgets.pas(2465,22) Error: Calling convention doesn't match forward
gtk3widgets.pas(93,14) Error: Found declaration: _AddRef:LongInt; StdCall;
gtk3widgets.pas(2470,22) Error: Calling convention doesn't match forward
gtk3widgets.pas(94,14) Error: Found declaration: _Release:LongInt; StdCall;
gtk3widgets.pas(3216,15) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(3225,15) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(3234,15) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(3454,17) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(3825,65) Hint: Conversion between ordinals and pointers is not portable
gtk3widgets.pas(4039,17) Hint: Conversion between ordinals and pointers is not portable
gtk3widgets.pas(4063,48) Hint: Conversion between ordinals and pointers is not portable
gtk3widgets.pas(4085,60) Warning: Conversion between ordinals and pointers is not portable
gtk3widgets.pas(4407,15) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(4530,6) Note: User defined: to get this correct we must use TQtWidget.CreateFrom() for scrollbars
gtk3widgets.pas(4762,34) Warning: Local variable "AIter" does not seem to be initialized
gtk3widgets.pas(4774,15) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(5222,55) Hint: Conversion between ordinals and pointers is not portable
gtk3widgets.pas(5223,50) Hint: Conversion between ordinals and pointers is not portable
gtk3widgets.pas(5252,19) Hint: Conversion between ordinals and pointers is not portable
gtk3widgets.pas(5261,26) Hint: Conversion between ordinals and pointers is not portable
gtk3widgets.pas(5813,65) Warning: Local variable "Cell" does not seem to be initialized
gtk3widgets.pas(6016,28) Hint: Conversion between ordinals and pointers is not portable
gtk3widgets.pas(6016,72) Hint: Conversion between ordinals and pointers is not portable
gtk3widgets.pas(6017,31) Hint: Conversion between ordinals and pointers is not portable
gtk3widgets.pas(6018,25) Hint: Conversion between ordinals and pointers is not portable
gtk3widgets.pas(6019,25) Hint: Conversion between ordinals and pointers is not portable
gtk3widgets.pas(6020,36) Hint: Conversion between ordinals and pointers is not portable
gtk3widgets.pas(6021,30) Hint: Conversion between ordinals and pointers is not portable
gtk3widgets.pas(6021,83) Hint: Conversion between ordinals and pointers is not portable
gtk3widgets.pas(6077,17) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(6276,15) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(6502,64) Warning: Symbol "add_with_viewport" is deprecated: "since 3.8 use add"
gtk3widgets.pas(6565,15) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(6659,50) Warning: Symbol "add_with_viewport" is deprecated: "since 3.8 use add"
gtk3widgets.pas(6779,23) Hint: Local variable "MsgActivate" does not seem to be initialized
gtk3widgets.pas(6810,15) Hint: Local variable "Msg" does not seem to be initialized
gtk3widgets.pas(6888,48) Warning: Symbol "add_with_viewport" is deprecated: "since 3.8 use add"